Why do I owe you a fulfilled promise? Because I said I'd be honest? Why do I owe you honesty about my honesty?
Reductio ad absurdum
If I build a search engine and promise that it will give accurate and honest results to your search queries, and then it doesn't do that... why do I owe you? "I didn't force you to trust me" is the most childish way to try and weasel out of broken promises there is.
To answer your question though - they don't, but it makes them a shitty company to lie to/manipulate their users.
You'll probably figure out at some point that they do, and that this whole law thing is a proxy for ethics we put in place so that we can punish people that don't.
Until then, live in your world.
The only real solution is to regulate this to make competition fairer again.