Four wheel disc required for ABS?

Are four wheel disc brakes required for a car to have ABS? This came from a dealer when discussing the problems with rear disc brakes.

Not at all.

My father has a van with ABS that his discs on the front and drums on the back, and I recently drover a truck with 4 wheel drums and ABS.

Ok, I didn't think so.
Since we on the topic of disc, what's with the problems with rear disc brakes?? I understand dust/dirt is the problem.

"Problem"? The only problem with rear disc, as far as why they aren't more common, is because they are more expensive.

Looking at Consumer Reports listing of brake issues on Impalas for example, they are almost all full black circles. The Impala has 4 wheel disc.
This was also confirmed by a couple of mechinics that admitted excssive problems with the rear discs. Even in the manufactures seminars, the topic has been brought up more than once. GM doesn't seem to know exactly what/where the issue is. The issue also includes Ford & Chrysler.

hehe, there's plenty of things the american car companies have trouble with :D

Yea, cheap labor from abroad.

I can't say I see this overrepresentation of rear disc problems on the cars I work on. Really, rear disc is a lot less stressed than the front disc brakes. Rear disc brakes have been in use for decades. If some car model has problems, its because they engineered them badly.

Drum brakes are used on the rear because they work better with a cable handbrake.

Most cars which run disc on the rear have a drum brake either inside or beside the rear disc rotors which is only used by the handbrake. This doubling up adds to the cost and complexity of the system.