I don't know of any case in industry where TLA+ has been used to prove a spec correct. AFAIK it's only been used for model checking. Read the "Formal Methods at AWS" paper for details.
If H1-B holders could freely change employers then I'm pretty sure that Amazon for one would be a better place to work. As far as I could tell they could only get away with treating engineers like they did because the latter had nowhere else to go (the vast majority are H1-B holders, not because of any local shortage, I suspect, but because they are so exploitable).