Do side markers have to be reflective?

Do side markers have to be reflective?

I thought the purpose of sidemarkers was to let your car be visible at night. Some cars looks like they have lights, others reflective. Both accomplish the same end, but maybe I overlooked the cars with lights being reflective since it's at night. Yes, they must be reflective.

Otherwise if your tail light is broken and you don't notice it, but it's not reflective yet, then you'll be very dangerous, you'll be easily rear-ended.