When someone in that industry tells me the machine is broken, I presume they're being dishonest because it benefits them (they avoid fees and presumably tax reporting to the income) and I've seen too many cabs have their machines magically working if you tell them it's CC or they aren't getting paid.

Also, if the machine actually isn't working, they always used to have paper slips to make CC charges. Those are never mentioned unless you tell them it's CC or they aren't getting paid. Dishonesty by omission is very much still dishonesty, and telling someone that the CC machine is broken implies that they can't accept CCs at all.