Rarity?

The one thing drums do have over discs is the surface area the shoes have against the drums. It is a LOT more than what disc pads have against the rotor. I "guess" maybe that's where they myth came from. Now, if somehow drum brakes could dissipate the heat quicker than discs, then maybe the drums would be more effective. Maybe. Maybe not.

I do know this as a fact. Drum brake systems are usually lighter than discs.