When I was younger I briefly flirted with the notion (and eventually decided against) of working abroad as a dev and came to the conclusion the UK has the worst software engineering salaries in the developed world. For an American, finding a low COL area to settle in and working remotely seems like the winning play.
I was stationed in Germany while in the Army and always wondered how Europeans manage to make ends meet. Compared to the US, prices are higher (since adopting the Euro, at least), taxes are higher, but salaries are lower.
US troops are given a cost of living allowance (COLA) while stationed in Germany. It is (or was while I was there) tied to the USD/Euro exchange rate. Even so, we always tried to avoid shopping "on the local economy" and stick to base facilities for groceries and such as much as possible.
- Social security is far better. You of course need to save for bad times, but getting sick will cost you practically nothing (you're always insured and the insurance will pay you 2/3rds of your wage) and when loosing your job (which is already far harder than in the US) you'll be covered quite good for 18 months and fall back to basic social support after that
- Generally a bit lower standard of living. It's not bad, of course, but 100k$+ cars, for example, are usually only leased via work, and 2k$+ laptops are a rather large expense to many people.
I don't think the salaries here in Spain are anything to write home about compared to other developed countries, but they've gotten significantly better over the years.
I consistently see JavaScript SEng roles at startups and large companies going for 40-60k.
The big cities are quite expensive, and you're not going to buy a mansion with that kind of money but it's still pretty good, especially compared to the national median.