One of my unfavorite random car regulations is that as of some time in this millennium, cars sold in the USA may not have required lighting on movable bodywork.

This bans new cars from having clamshell bodywork like that found on classics like the Jaguar E-type and Ford GT40. I suspect it also results in many cars having narrower truck/hatch openings than they would have if they could put mandated lights on the trunk lid or rear hatch.

It's not hard to imagine the partially legitimate reason that on occasion, someone will drive with the trunk open, but do we really need a law about it?

> It's not hard to imagine the partially legitimate reason that on occasion, someone will drive with the trunk open

No, it's a much more serious and likely reason -- people stopping on a highway at night, getting out, and opening their trunk for some reason (like a spare tire, fluids, etc)?-- then their lights (and the reflectors in the lamp housings) are pointed at the sky.

Your post reminded me of a video on the an imported TVR Tuscan, filmed by Doug DeMuro where he covers this too. The TVR Tuscan is one of those cars where if the rear trunk is open, you can’t see the turn signal lights. In the video it is claimed that because of that, by laws in the UK, the trunk must have a triangular exclamation point sign as a safety precaution to let other drivers know when the vehicle is immobile.

That is around the seven minute mark of this video: https://www.youtube.com/watch?v=32u6KPTALxg

Every safety regulation is written in blood.

That particular blood was probably people stopped at night with the trunk open to access a spare tire or tools. And then there was more blood because sometimes those people forget to leave their lights on, or their lights don't function because the battery has died, so we got more regulation requiring ugly reflectors.

And so on.