Short of regular 3rd party audits, there's nothing they can do that would assure they're handling your data with privacy and care. And even that's a stretch.

The only way you should trust them, or anyone else, is if they don't collect your personal data at all. There is absolutely no way I'd trust any website or service with information like what they want. All of these laws are explicitly designed to create a digital profile of every person so they can track what you do. It can't be done ethically because it isn't supposed to be done ethically.