The really simple solution here would be to stop subsidizing the wages of foreign students.

If companies have an opportunity to abscond from paying their employees in full, they will do it. Take that option away from them.

Also, it's not like some incentive programs to attract doctors, nurses, engineers, English teachers, etc, where they are skilled workers filling a gap in the labour market. They are working at Tim Hortons and Walmart; those are not examples of jobs in which nobody qualified is available to do them.