Michael Chare wrote:

is it really the
case that a rear light unit with LEDs and driven by CAN bus, with two
thin wires for the power and two even thinner wires for CAN-H and CAN-L
bus is really cheaper to make than one with convention bulbs and much
thicker wires?

Well yes, because thick copper is expensive, and those 4 wires (and
multiple CAN chips) can individually drive
tail/brake/indicator/reverse/fog lamps ...

Also the chips start to do snazzy things such as dimming one side's
front running lamps when indicating or providing the "moving pulse" on
newer indicators