It's true, I do think that a more principles-based approach is usually preferable. (And I will happily marshal anecdata to that end!)
But it's naive to think that any approach comes without a cost. Even the PayPal example I mentioned above could be coloured the other way: A company makes a major investment in a foreign market, only to find the rules changed underneath them by a capricious government agency! (Someone brought up IR35 down-thread, and that's an excellent example too.) Is that an acceptable cost for the outcome? I'd look at the overall state of (eg) consumer financial protections in the US vs the UK and say "yes"; but I'm open to evidence-based disagreement.
This sounds like it would make an interesting blog post!
Edit: I realized this might sound passive aggressive. I like the idea of human judgement in regulation, but I really want to know what checks are commonly used to account for all actors involved potentially being malicious.