One reason for this may be that they are cheaper for their employers although they falsely sell themselves as native speakers from the US! All of them involved in this show are crooks! To be fair, it is also often true that these Eastern Europeans are often better trained with much better qualifications than real Americans - a lot of them who can't even count till ten and show poorly written English for a native speaker.

"I'm not doubting what you say, just saying that there's another reality living alongside. What is a bit scary is the Chinese employers seem to prefer the Made-in-Ukraine-never-been-to USA-yanks to the real thing and also to the English and Aussies, etceteras."