I'd like to see at least some evidence of the "net negative impact". In the case of slaughterhouses, it impedes the local and smaller-scale (and possibly more-human) commercial slaughter of animals. But slaughterhouses should probably, in general, be regulated. I'm not sure if extant regulations are net negative or positive. But I know that their complete absence would probably be bad. It's not a matter of existence, it's a matter of implementation.

I'm not sure it's net negative in the case of the GDPR. As a sibling (cousin?) poster said, good riddance. No company should be allowed to mismanage my personal data, big or small. Until I see evidence that GDPR compliance is cost prohibitive enough to suppress startup formation, I won't be convinced that the tradeoff isn't worth it.