Not to side with this behaviour, but I think if you consent to it in the Ts & Cs then it's legal. And that makes sense - otherwise how else do you agree to things or not agree to them?

The point of laws is that T&Cs don't matter if the law has something to say. If the law e.g. were to criminalize sharing health information in this way, then it doesn't matter if the users agreed; you still go to prison for doing it.

> if you consent to it in the Ts & Cs then it's legal.

No. In a paper contract, you can scratch off things you don't agree with. You can negotiate.

You can't do that in Ts & Cs. For example, Ts & Cs often unilaterally change with no ability for you to review or cancel or undo. It's trivially easy to write software which uses services without ever agreeing to Ts & Cs. So it's not really a legal contract.

> And that makes sense - otherwise how else do you agree to things or not agree to them?

Through a real negotiation. With a paper contract, that both parties sign, and both parties receive a copy of, and that can't be unilaterally changed.