One could play devils advocate and ask "What would 1st year FO pay be at regionals if there wasn't any Union?"
At the end of the day, sorry to say, the issue deals with people willing to do the job for the set pay. It is not rocket science to assume that if applications stopped tomorrow, pay would have to increase in order to attract the fewer number of applicants for the job. Management has already bumped up signing bonuses, "flow agreements," and the promise of quick upgrades to help get pilots to their airline. Sadly pilots go for this. IF they were to refuse these "carrots" by managements, Id have to assume that the increase in monetary compensation would have to come soon after.
The Union can not stop people from applying and trying to get hired for the low wage that is currently being offered. If unhappy about the low pay for First Officers, stop by a new hire indoc class and ask those in attendance why they sell their skills so cheaply on the open market.
Guys like Ornstein are openly vocal about knowing this and taking advantage of it. And why shouldn't or wouldn't they?