I never had to get vaxxed going into Cali and I had a dedicated route to LA at the time. You try getting truckers to do something they don't want to do. They'd just stop going to Cali.

I remember hearing an intermodal company talking about how the shipping companies stopped taking empty containers overseas for a spell, so it got to the point where no one could pick any full containers up because they couldn't get the empties off the chassis. That was more likely the cause of the supply shortage.