When I was at Comair, I flew with several Very Old and Very Senior pilots. The Top 300 at Comair are for the most part topped out on the pay scale... meaning 18 years of longevity (excluding the 89 days). Some of these people were hired at Comair before ALPA was on property. These Pilots explained to me that if you are at a company before a union is.... you have a choice weather to join or not. IF you choose not to join you pay NO DUES. Correct, you do not have access to services... but you owe the union no money and they have NO RIGHT to get $ directly out of your paycheck without your permission.
However, if you do choose to join the union. You Can not decide later that it was a bad idea and opt out. If you join the union and then quit, you are part of the closed shop and will still pay dues.
IF Skywest votes in a union, I think that many people there simply will choose not to join the union from the beginning and ALPA will see very little dues benefit.
At Allegiant there have been a small number of people talking about getting ALPA and from what I am hearing ALPA will only put together a serius drive if there is 85 - 95% pilot group backing for it. IF ALPA passed by say only 51%, there would be 49% of the pilot group not paying dues..... Not subjected to Closed shop rules. Only New Hires would be involuntarily committed to paying dues.