Solidarity doesn’t have to mean they like have a club with a secret handshake. Their goals are aligned, and they tend to work towards those goals, even without explicit coordination. It’s rare to see anyone in the ownership class work against those interests. You don’t see a lot of the owners saying “we should give people more time off” or “we should let the workers have a say”. It’s pretty consistently “we should squeeze people for more money”. It makes the news when ownership is like “We’re going to pay people more”, and it doesn’t make the news when labor is like “i’ll just work a little more off the clock to catch up”.

Contrast with labor, where people are often undermining their interests. Being anti-union, voting against regulations that would protect them from exploitation, giving away labor for free.