I was thinking about this a bit more.

Bicycle lighting is one thing that DOT hasn't fully regulated for some reason. There is usually a requirement for lights, and some kind of a minimal candlepower. But, since they are often powered by batteries, the brightness can vary considerably. They are also local laws, and not federal regulations.

Blinking rear lights, and sometimes blinking front lights are pretty ubiquitous here in the USA. Blinking lights are illegal in parts of Europe. But, I think some countries also regulate lights much more, including requiring generators, or lights on some bikes 24 hours a day.

Perhaps it is time for the Federal DOT to start evaluating bicycle lighting. Also reflectors. I usually don't use spoke reflectors, but I'm happy with tire reflectors.