MEC's and LEC's are not compensated--it is volunteer work. Members of the safety committees, jumpseat committees, scheduling committees, hotel committees, communications committees, negotiating committees, etc are all volunteers. Most work long hours on their own time. Now there are stipulations about being given the time to attend to Union business--but there have been instances in which the company has denied it.
Dues go to ALPA and they seem to enjoy compensating themselves. If you are interested in the financials of ALPA, they are disclosed annually per the Labor Management Reporting and Disclosure Act.