I'm have to be compliant otherwise I would get de-ranked by google. I have all Privacy, Cookie, Third Party Policies CLEARLY displayed. It's also the users option if they want to mine and how much CPU they want to use. I also tell them about the damage that can be caused to their device with prolonged use. My members get shown their HASH RATE and the subsequent earnings from their hashes, I just keep a percentage that is also clearly displayed to te user.
I have a lot of websites and a lot run google ads so I wouldn't want to get blacklisted. I also work with legitimate partners who I also wouldn't want to get banned from.

People that don't tell users such stuff can't be bothered doing a bit of hard work and want to try and cheat users and partners and are usually banned from all the legitimate ways to earn. They learn the hard way.