There is a difference between paying for your own basic training - similar to paying for your own degree, and paying for your type rating (equivalent company specific training, housemanship for doctors, etc.)
Before becoming a pilot I was an engineer. My company paid for my degree and I was expected to work back for them for an equivalent period of time. (bond) During the first 2 years I was an engineering trainee and spent most of the time on training courses at company expense. During this time I was paid a salary even though I added very little value to the company.
I can think of no other industry where you are expected to pay for your company training once you have qualified. First of all you can't choose what aircraft your company flies so you are obliged to do the type rating on the type that they operate. The airline should pay for this since it is in house training for their own specific operational requirements. If they bond you for this training - fair enough, although I cannot think offhand of any other industries that do this. Doctors dont pay for their postgraduate training. Nor do engineers, architects, lawyers, plumbers, builders etc. etc.