[bpt3]

The gap is much smaller for private sector workers, and it's somewhat self-selecting by the fields where a union exists at all.

If I'm one of many types of service worker, sure I very well might join a union because I'm pretty replaceable and my income has little to do with my individual performance. I'll do better by forcing my employer to collectively bargain on terms that are relatively favorable to me by law.

That doesn't mean that all tech workers should support unions entering their field.