Ok but what about when companies like Uber break the law and it's celebrated? Or when the law gets changed to protect existing companies from competition like Tesla's competitors have been successfully lobbying for?

Unfortunately, it's not as simple as the "law" but more of "is it worth enforcing?". If you look at the stories of successful startups including YC ones, you'll see a history of unfair advantage early on to achieve initial traction or press. If their intent was misconstrued as malicious, it wouldn't be too difficult for someone to take them to court.

Some examples -

1) P2P file sharing & video hosting sites gained their meaningful traction by dealing with copyrighted content in a very hands-off manner

2) AirBnB & dating sites taking existing customers from popular sites to move them over in a way that goes against TOS