Huge wrote:

Sadly, so I have been told, a lot of the cheaper readers do not
implement CSMA/CD

I suppose for a payment terminal, you don't want to talk to more than
one card anyway, though some do seem to detect it, I've had them say
"only present a single card" OWTTE, maybe they just detect that by
garbled communication?

if that's what the "prefix creep" can be described as.

I think it's proper name is anti-collision