I thought most truckers, owners or otherwise, belonged to the teamsters.
Nope! I would never join a union. I ain't paying dues for something I don't get anything back from.
A lot of "local drivers", and dock workers were union depending on the area, and 100% of the time, were a pain in the ass to deal with.
As a general rule, local drivers get paid by the hour, while long haul pays by the mile, or a percentage of the load.
I leased my trucks on to a company, that got my loads for me. If I didn't like the load, or destination, I'd turn the loads down.
The companies I chose paid my tractors by the mile, and also furnished the trailers, while I furnished the power units, and teams.