When I worked tech support for a company who serviced big banks, several banks had requirements that we had to be US citizens operating in the US to access their systems and access to information about their systems.

(amusingly over time they started to outsource things and they kept our rules but their people would call us from overseas :P)

Work for several US contractors required the same plus a security clearance.

I'm not opposed to these kinds of rules for some things. I think they're a wise choice.