This happens at a much smaller level too. We knew an au pair that the host family particularly liked, and wanted her long term. A typical au pair contract is for 1 year, maximum is 2. They worked with an immigration attorney to craft a "job" that she was uniquely qualified for, went through the whole dance, and got her into the system. She stayed with them for the next 10 years. They covered room and board, but she worked for free otherwise; getting her in the door and on the way to citizenship was her "pay".
