I would assume the cost of a license to be much, much smaller than the actual cost of raising and training a service animal?

Generally there are charities/non-profit organizations that will do a lot of the training and help with the ongoing costs of care.

I personally don't see the argument that a separate license is needed or helpful. It's an extra cost and step that's entirely unnecessary. If you want or need a service animal you obviously have to have some way to train it and care for it, but a license is extra. Also if it is ever lost or anything you could be turned away from any public place until it's resolved. I just see it causing more issues for people than it tends to solve.