A lot of people are involuntarily in unions because of “fair share” laws. I will bet that is the case with these Scott Brown supporters.
I began my accounting career in county government. Membership in SEIU was a condition of employment. I went to a couple meetings to see what it was all about. The local member/officers ostensibly ran the meeting but a couple of times they had trouble making the "correct" decisions. It was then that a guy sitting quietly in the back of the room spoke up and got them back on track. Turns out he was the SEIU pro. He had effective control of the meeting and the decision-making process. The handful of voting members at the meeting only ratified what he had already decided. The vast majority of the local membership had no idea what was even going on when it was decided to donate union money to the leftie on the Board of Supervisors who was running for California State Assembly. And this was before he had even officially announced.
But I would never have been caught dead in an SEIU teeshirt.