There are temporary or limited term part-time jobs, though. There is no real need to hire and then fire folks. Simply hire as a seasonal employee. This is what retailers do around Christmas, for example. Sometimes they'll hire an employees a permanent employee afterwards, but not always. There are folks that take these jobs year after year - both around holidays and during summer breaks. Sometimes this isn't ideal and sometimes it is pretty perfect for the employee.

But these are not contractors. They are employees. The company pays all of the applicable taxes and handles payroll. The company is responsible for workplace injuries and so on. I don't see where this is really a big issue - and hiring these folks as contractors seems more a thing to take advantage of folks.