Burned-out LEDs in Prius brake lights?

I've noticed some Prius G3 cars with burned-out LEDs. Yesterday I saw one with just one "square" of LEDs burned-out, and today I saw one with the left-most row (5 squares vertical) inactive but the other 7 still working. Do cops pull-over owners if the brake light still works, but is partially burned out?

How much is the replacement cost? I imagine it isn't cheap. I would hate to be stuck with a huge cop-induced bill because only 1 or 2 squares were unlit, but the brakelight worked otherwise (alerts drivers you are stopping).

 

I'm shopping for a Prius G3. I'd really like an answer before I lay-down a lot of money, so I can estimate future maintenance costs. (Well not that much: ~$10,000 used.)