If we don’t trust the people we work with, how are we supposed to organize?

So far I've seen two posts about not trusting your co-workers, and honestly that doesn't make any fucking sense. I'm not saying you should trust everyone or that there aren't people out for themselves, but completely distrusting and never sharing anything with your co-workers is completely counter productive to the idea of any labor movement. What is the fucking point in calling for solidarity if you're just going to isolate yourself?