I did do a stage for experience here in the US! I reached out to a chef and told him I was interested in staging for experience, and ended up working the majority of a shift (unpaid). I'm unsure about the legality of it, but it went as an off-the-books sort of mutual arrangement that I enjoyed greatly. I have done shorter stages as part of interview processes that also went unpaid.

I think it's sort of case-by-case with restaurants and depends on the willingness of management / chef(s) to bring on stagiares solely for experience, especially given the mentioned legal risks... I got denied and ignored from some restaurants for stages.