"Michael Chare" wrote in message
news
I presume cars are made a economically as possible, so 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?

Yep.

The modern system does not make connecting a trailer light socket easy!

It does when it is designed to handle a trailer.