People talk about immigrants needing to learn English like this is a new situation. When I was growing up in Cleveland, Ohio, fifty years ago, there were a number of neighborhoods full of people who did not speak English. If a job does not require much communication, I do not see much need for the people doing the job to be able to converse in English. I can see requiring enough English that the job can be done. If you want to converse with your manicurist, then go to a shop where people speak English. It does not need to be a job requirement. If the manicurist cannot communicate well enough to do the job properly, then, by all means, complain to the manager and do not go back. If you see unsafe practices, again report it to the manager.
As far as the number of hours of training required --250 hours seems excessive to me. I was looking recently on requirements for a Commercial Driver's License and there are no requirements for hours of training, just the written test and the road test.