Does the fact that a visa is granted for a single employer give that employer a lot of power? To all intents and purposes, if the employee is not satisfied with his working conditions, he can't go elsewhere, unlike a Canadian employee, who, if he isn't happy with his employer, especially in the context of a labour shortage, will go see another. That's all.
Would we be solving part of the problem if we granted a visa, for example, for an occupation in a province, which would enable temporary workers to change employers if the latter didn't act properly?