Exactly. That all sounds infinitely easier than buried air pipes. Mind boggling physics are what gives us CPUs, but the final product is reliable bar none.
Meh. Fiber has been cheaper than copper per mile for a long time and 10km optics are like $20.
yes, but this does not scale if you want to build residential connectivity.
GPON makes this scalable and affordable, but at the cost of technical complexity. Fiber (as in, the cables themselves) is far cheaper to produce compared to copper, but this has mostly to do with the price of copper and not manufacturing techniques.
ADSL is basically modulating a radio wave over a cable directly to another device. Fiber requires high quality optics, high quality lasers, tons of active hardware if you want to do it at scale. (not to mention the mind boggling physics and manufacturing required for things like DWDM, optical path switching etc).
Fiber optics have existed since the 80's yes, but prices of high quality fiber solutions have only dropped massively in the last decade or so.