ALPA on a Major level works.....some agree some don't but it does.
ALPA at a regional not so much.
You can't have one union representing two carriers who compete for the same contracts. So ALPA signs off on airline x for say a cost off 10 bucks an hour and later signs off on airline y for 9 bucks an hour. Y ALPA just undercut X ALPA. Now Y carrier has huge growth because they can do it cheaper while X airline stagnates. If ALPA would demand the same pay and contracts thats the only way they could represent both x and y airlines.