It might be an executive thing?
(This would include companies like Sony, Nomura, Toshiba, Honda, BMW or even Saudi Aramco - all having US subs)
When I was in China, the Indians working tech there were referred to as expats just like the Germans and British — because they didn’t have any intent to permantly relocate to China.
Not everything is a racist conspiracy. Intent of the foreigner is the key factor in their expat vs. immigrant status. Generally people immigrate from poor to rich countries, because they would prefer to live permenantly in a nicer place. Immigration the other way around is quite rare. Not a lot of British are clamoring to immigrate to Bangladesh: a Brit working there would rarely be called an immigrant because they aren’t. They’re an expat. They have no intent to make Bangladesh their home. A Bangladeshi on an H1 visa almost always has a green card and eventually citizenship as their goal: thus they would be immigrants.