Basically it is because it is a US company. I got the job after I moved to Croatia. In this case, you generally need to be hired on as a contractor. Of course, your employer needs to know that you are a US citizen and you are living abroad, for US government tax reasons.

The way it works is that you basically look for contractor jobs that are remote-only, that are based out of the US. You ask them if they are willing to take on you, a US citizen with US-based work credentials, working abroad (in X country in Y time zone), as a contractor.

The key is that you need to get a local (abroad, where you reside) payroll company to do the taxes (as an intermediary) between you and the company. Technically you can do the taxes yourself, if you know what you are doing, but usually this is the best way to approach it. It certainly looks better to your employer to do it this way.

I live in Thailand. One of the big tech companies here is agoda. If you have dual citizenship, and you apply for a job there and present your non-Thai passport (HK, SG, USA, etc), your job offer will be for significantly more.

I like your username given this context.