All that being said - I know Stevie is an agency driver (as I am). And he is working for a reasonably decent firm.
I can’t see any union having any interest in helping an agency driver. It’s not in the full-timers interests for you to be looked after… I’ve never met an agency driver who is part of a workplace union. And I have certainly never been asked to join one.
Conceptually I’m all for unions - and I think they can be a good thing for both the driver and a company. All I shall say is what I see in reality isn’t that… More like babies threatening to go to the union if they don’t get the truck they want, or the run/shift length they want. An insult to the men who joined unions historically so they could earn enough to feed their families, or to get companies to provide basic safety procedures to stop unnecessary deaths.