Power lines aren't an inherent fire risk. Unmaintained power lines, however, are.
Primarily, you need to maintain clearance from bushes and trees.
The exception to the "usually only" is, once again, our beloved "german redneck" government in Bavaria who insisted that the new North-South line Südlink got buried on Bavarian soil to quash local NIMBY resistance [2] - at the price of taking ages longer to build and costing ~8x the amount of pole-run lines.
[1] see page 64, https://www.amprion.net/Dokumente/Dialog/Downloads/Studien/E...
[2] https://www.sueddeutsche.de/bayern/energiewende-warum-erdkab...
and due to the way the laws are written, we had to pay to have an engineer prescribe what work needed to be done to each pole - up to and including replacing it - then submit plans to the utilities, and then pay the utilities to pay 'their' engineer to do the same study - and then when it was agreed that a pole needed to be replaced, we had to pay the full cost of replacing it, and then when the work was done, the utility still owned the pole and rented it back to us for a yearly fee - repeat several hundred times.
Several million dollars for about 500 households.
Orders of magnitude. I actually once worked in construction, specifically in trench digging for German Telekom.
Putting up poles is easy, drill a hole in the ground for the pole, put the pole in, string a fiber on it, done. Even cheaper if you already have poles, all you need there is a truck with a lift. Downside is, unless you own the poles, you have to rent them from the local utility and some of these charge extortion rates for third parties. And there are always drunkards or people with shoddy cars taking down entire series of poles, not to mention adverse weather events and vandals taking pot shots. Phone and electricity lines are easy to fix, you can probably train apes to do that, but splicing fiber still involves specialists.
Trench digging is a whole different beast: you need to pull permits, dig the trench, hope you don't hit something else that's buried, deal with bad soil (sometimes straight out rock) or shit like WW2 bombs, lay down your cable, bury the cable in a first layer of fine sand, place a warning band, bury and fill up that with the coarse soil you removed, restore asphalt/plaster where needed... it takes weeks and multiple dedicated crews - usually you have one crew that deals with cutting up and removing asphalt, one that deals with placing and removing anti-traffic barriers, one with doing the actual dig and backfill, one that runs the cable, and one that restores surface.
There is a third way however, it's virtually "underground poles" - earth displacement hammers. These "rockets" can shoot up to 70m through the soil in one go. Nice shit but needs the right soil to operate and it will cut through anything already buried, including solid water and wastewater mains.
Does any of this calculus change when you're talking about really rural areas, like in the desert of Australia? My guess is that would mean higher cost of sending someone out to fix a pole (point against poles), but also lower likelihood of running into existing infrastructure (point in favor of digging).
For power at least, running it buried is no good idea at all because capacitive losses are larger, so at least as long as an area has a grid connection it makes sense to "dual use" the already existing poles.
Based on popular memes I can imagine, especially in Australia, that it might not be a good idea to bury lines in the open desert because you will get animals burrowing and chewing through the cables.
Putting Germany in the same category as Australia or the US seems a bit weird when the former two have truly continental dimensions whereas Germany is a bit smaller than California, although there's an interesting twist: Going by population-weighted density, Australia definitively comes out ahead and even the US is somewhat denser than Germany in that regard.
Though on the other hand the United Kingdom is much denser population-weighted-wise than all three of them, and yet from what I've gathered it's no perfect shining example of highspeed broadband rollout either…
I believe there will still be a rural segment relying on cellular for a while yet, but it's a shrinking minority.
Economics aren't actually that different for villages (very rural single dwellings are though of course). Most villages of say 1k ppl already have fibre going to them (for VDSL cabinets), so they can buy the backhaul from Openreach.
Then it's a case of adding the actual fibre which they can use existing telegraph poles for.
There isn't really a huge difference in economics between urban suburbs and villages.
London is actually not as cheap as you'd think, because a lot of properties are apartments and that requires expensive wayleave agreements to be negotiated with the freeholder. This has significantly increased the cost, as many freeholders don't care and don't respond or want a lot of money for the permission, meaning you have to dig up the street regardless and miss a lot of properties and hope they can be added later.
Plus the cost and complexity of closing roads/streets is much higher in London than other areas.
In the past few years though there has been an explosion in FTTH build. 75% properties can get gigabit service now which is increasing by around about 1% every month.
The priority a decade ago really was on getting the entire country up to 'usable' internet speeds, rather than having a lot of FTTH in some areas and then very slow DSL in many other areas. Only 0.35% of UK properties are below 2mbit/sec down now (unusable), which doesn't include 4G/5G coverage, so in reality it's likely only 1 in 1000 households have utterly terrible connectivity.
So while the UK doesn't rank top of the list of median download speeds it is far less likely you are going to have bad connectivity, which IMO is a greater priority than raw download speeds.
Very few people actually need more than say 100mbit/sec day to day. It's actually hard to get gigabit around the house; most powerline adaptors and wifi solutions top out around 300mbit/sec in my experience, so unless you have ethernet in your house (very rare), the limiting factor is now on in home connectivity, not the external ISP.
It's not that it's economically infeasible. It's that it's just not as profitable for the ISPs as running a smaller, closer network in a populated area. So they won't do it. Why would they care about covering a huge area that doesn't make as much money? All they care about is money over all else.
Partially. The thing is, the US is so unbelievably huge that it is economically infeasible to serve extremely rural areas with high-speed wired (i.e. fiber, DSL) or wireless (microwave, 4G/5G phone) internet, even with massive government subsidies - and that applies for other large-area countries such as Germany or Australia as well.
Starlink completely changes the equations there as (for the user) no investment is required other than getting a terminal, and for anything mobile (sea ships, RVs, emergency services) it blows the competition from geostationary satellites completely away.