I had a Seiko SKX-007 that needed some 
    maintenance, and I was quoted $600.

That price is awfully high. They were either trying to rip you off... or simply drive you away, which is possible if they were a shop that prefers to work on high-value watches for wealthy customers. Maybe they are an authorized Rolex service center and prefer to collect those hefty prices.

But, there's definitely not $500+ of labor involved at any reasonable market rate.

Those Seiko 7S26 movements are something like $50 new and even an amateur can perform the swap in a short amount of time without specialized tools (edit: well, maybe a hand puller, but that's cheap) and there are plenty of videos showing how.

There's no actual watchmaking knowledge required. That would only be required if trying to repair a module rather than simply swap it out.

The SKXxxx models are something of a classic but are hard to find now that they've been discontinued for a while; if you still have your broken model it may be worth more than you paid for it.

It was definitely a high end watchmaker. A large part of the issue is what they considered the service requirements, that they wouldn't budge on - things like polishing all the scratches out of the band, and whatnot, when all I really wanted was maintenance on the movement. I didn't want to swap the movement, and that wasn't an option either.

I once serviced a Rolex Datejust with diamond dial and gold bracelet for almost the same price. (Depending on exchange rate)

I’ve looked into this and the only recommended tools were a hand puller and hand press, otherwise it’s pretty straightforward to replace the movement with another stock one, or switch it out to 4R36/NH36 to add hacking and hand winding. I plan to swap the movement for one of the hacking/handwinding ones when the movement when my SKX009 dies.

I think about this problem often. I think it's caused by economies of scale and is an escapee of Pandora's Box that we're not going to be able to put back. Instead, we need to think carefully about what we build and how we build it - educate consumers, regulate to price in obsolescence and recycling costs, and place greater value on long-term quality as a society - to prevent this from growing even worse.

I build industrial automation equipment, so I'm in part to blame for the problem, however, I'm also in a position to advocate for easier repair processes and more sensible assembly stackups. It's simply a fact that the six figures in initial equipment capital divided by, hopefully, a similar number of unit sales, plus the few dozen seconds of operator hands-on time per unit, always going to produce an end product which costs less than hours of diagnosis and maintenance by a local, high-skill repairman. The math simply doesn't add permit any other arrangement, no matter how standardized your tooling is, how open your repair manual is, or how efficient your aftermarket parts ecosystem is.

Repairing and maintaining something for more money than it cost to produce it puts those activities firmly in the realm of luxury goods. The better we get at producing useful things cheaply, the more we have to multiply the value of human labor, and the less it makes sense to repair cheap things with this expensive labor.

One interesting option today is that you can get an electronic watch and get access to all the internals as well:

https://open-smartwatch.github.io/

However, its operation depends on electrons and bits instead of springs and escapements, and you can see those bits moving about in PlatformIO code instead of under a magnifier.

I got into it after my smartwatches, oddly enough. I didn't wear a watch between the mid-90s young kid with a Timex Expedition and the late 2010's adult with an Apple Watch. It was getting in the habit of the smartwatch that made me desire to wear something different again.