If there is one thing that is incredibly complex, it is fire codes - in no small part because these vary from town to town, or to be more precise, the height of their portable ladder trucks. Once you build higher than these, you have to plan for a second escape route.
That's not that bad of a thing if you work exclusively in one area... but good luck if you operate across the nation or, worse, internationally because everyone does things a liiiitle bit differently.
Have you ever been the responsible person for a public building, a big concert or anything of that ilk? Suuuuure, fire and work safety are easy peasy, uncomplicated and totally trivial compared to the GDPR. And the laws and regulations involved are so incredibly brief, well-written and stay consistent over a long time... o_O
/s
Even with a small pub that you run with your friend, you have to deal and comply with fire safety, toilet, public health and a whole lot of other codes.
Fire safety is less onerous and less complex.