Rear LED Tail Lights

[Mike_H]

Just guessing, but the forward voltage drop of a red LED is about 2 volts, so I would say each vertical column of 4 leds are in series with current limiting then the 5 columns are in parallel. Or it could be by the row of 5 LEDs x 4 rows. In either case, one failed LED in series will take out the rest in series, but still leave lots of operational LEDs.
Same with the backup LEDs below.

Now you're making me curious. I'll have to look at the board and see what I can see in the circuit...