Is it reputation? Integrity? Is the reasoning purely financial?
Then ask whether the company operates in a way that suggests they'd do the profitable thing over the right thing if they think they might get away with it. Does that picture look realistic?
As an example, look at Apple. Leaving the tangential discussion about scanning iCloud photos for CSAM aside, they are a company that claims to care about users and about privacy. Whereas every other company is literally trying to send all data to the cloud, Apple is telling us they're working to process everything they can on the device itself.
What would happen if they were caught selling location data? Caught allowing companies direct access to data aggregated from users that they explicitly say they're not collecting? They'd stand to lose literally many billions of dollars of sales because the thing differentiating them from everyone else would be erased.
Which is greater - those billions of dollars of sales as a premium device maker, or those scraps of money they'd make from underhandedly selling data?
Now look at the same scenario but with Facebook, or Google - is it the same? No, because we have no realistic expectation of privacy with either company. They're in the news quite often because they're doing nefarious things, allowing access to data most people didn't even know they're collecting, yet people aren't really doing things differently because of the news.
Imagine the same with companies like ExpressVPN. How much would a disclosure hurt them? How much money could they possibly make by selling private data? Do they employ the kind of people who'd take the gamble between the two?