If it's anything like Sweden, working as a permanent employee for a company in the Netherlands with that salary also gets you relatively high job security, pension contributions, 6-8 weeks off a year, unlimited sick leave, sometimes a collective agreement with guaranteed pay bumps or bonuses, often additional wellness allowances, etc.

Some companies employ through a local entity which gets you some or all of those same benefits. Often that's not the case. Which is not a bad thing at all imo. It just means that $80k would probably not be high enough to be equivalent with what you'd get locally when it comes to total comp.

Side question: Do people typically get to use all those weeks off? I get 5 weeks off, but it's incredibly difficult to still hit my deadlines if I take any days off.

Not sure about Sweden, but in the Netherlands it's very normal to use the full 5 weeks. I think Sweden is the same.

That's not your problem, unless you are coming up with those deadlines yourself.

In my experience almost everybody uses their vacation days in NL.

It took me a while to get into the habit when I first moved to Sweden, but after a couple of years I did start using all my weeks. Having a really long (4-5 week) summer vacation really really helps with recharge and coming back more fresh and productive. Some people do end up with days rolled over into next year, but there's a limit to that accumulation after a few years, so if that's happening eventually managers and leads strongly encourage you to use more of those days.

In Euros maybe, it's 6k/month with 13th month, it's at higher edge but definitely not top 5%, the 50k would be below senior no matter how you look at 'senior'. In Dollars less than reasonable, especially since you do not want to be payed in foreign money if working remote. It also depends a lot on what kind of experience/education you prefer. If you want highly educated seniors with 'senior' level of experience (as in multiple years to a decade) the higher end matters a lot, NL is famous for underpaying engineers and overpaying managers and the better engineers have noticed.

Though without knowing all secondary stuff it's a wild guess anyway. What you describe in NL usually also benefits pay for pension (usually not included in gross salary specification), some form of mobility or at-home budget, and all other perks considered in-kind pay, maybe a lease-car at a larger company. Maybe that's included here, maybe it's not and that can make up several dozens of percents of pay.

Though "senior" means so little it's hard to judge what is meant by that though it looks like OP is specifying task-specific roles which lower the need for a jack-of-all trades, highly educated, years of experience a bit.

Not sure which city and how much experience those developers have. But we pay 80-100k per year base salary + stock options + pension to medior developers in Amsterdam. Higher for more experienced roles.