Tax-status aside, the IBT is most definitely a business. And while it's certainly true that Express workers sat on their hands for decades, a big part of the reason was an oppressive anti-union culture at FedEx that almost guaranteed termination for those that advocated for a union. That's illegal, but it has never stopped Express management from terrorizing those that understood Mr. Smith many years ago and wanted to stop him.
The IBT won't touch Express because Fred S has his RLA Kryptonite that will paralyze any effort to organize. While I strongly believe that a vast majority of Express workers would sign cards and vote for a union NOW, that wasn't the case even a year ago. R1a was correct when he said that the IBT isn't going to undertake a national Express organization drive because it would be a bad "investment". They don't see a payoff for them, which would be tens of thousands of dues-paying new members that would pump new life into a moribund IBT that is losing membership every year.
Until Smith's political power gets checked, we are up

Creek without a paddle.