The most annoying thing is that 75% of cabbies will always use the line "cash only, machine broken", trying to imply that their credit card machine is currently not working.
The funny part about this is that 99% of the cabs around here use the old school swiping method - they make a carbon copy of your credit card.
I heard from a friend that it is illegal to turn down a fare if they have money, whether it be cash or card, and I will argue with the cabby until I get my way. I have never lost.
I think they do this so that they don't have to declare tips, but that is just my theory.
Last weekend I had a cabby who said his machine was broken. We got in the cab anyway (miscommunication between friends... none of us had cash). Once we arrive we realize we have no cash and the guy FLIPS out. He says he has to take us to an ATM. After a few minutes of arguing we finally say fine, fuck it, lets go to the ATM. We get about 3 blocks down, him bitching the entire time, then finally he pulls over and pulls out his fully functioning credit card swiper.
I made him take me back home. Jackass.