Do other professionals have to pay for the training they receive once they are employed by a company. Take the army for instance. Imagine if we suddenly required people to pay for a tank rating before we interviewed them.
The problem is that once a person has spent the 90k mattyj is talking about then it is hard to not spend a bit more to get some form a return on the investment. Especially if you are a GA pilot who just wants to get a job flying an aircraft that is less likely to fall apart on you.