There is no "shortage."

I've been turning wrenches as long as I've been flying, and I know a number of others who have done/do the same.

If one doesn't want to put up with regionals, there are plenty of other places to go.

Aviation maintenance has notoriously paid low, and it's a lot more involved than what's required of an ATP. I often hear ATP's opining that holding the ATP is the equivalent of a doctorate in their field. It's not. It's the commercial and instrument rehashed, which is mostly the private pilot rehashed. The A&P ratings on a mechanic certificate, particularly with some experience behind them, are involved and require a great deal more complexity, to say nothing of liability. When one can take that training and experience and move from twenty five dollars an hour on the line or in a repair station to eighty dollars an hour at a car dealership, where do you think the worker will go?

There's no shortage of mechanics, but there's a shortage of good paying jobs, and there may be a shortage of good mechanics.

There's no pilot shortage, but we see employers crying about one; those who do are usually the ones for whom nobody wants to work; the only shortage of pilots seems to occur at their company. The same rings true for the maintenance industry.