I don't take the bus very often (my daughter stopped taking the 122 because it is so unreliable) but I can't recall ever having any kind of a hold-up because of people paying cash. I have had hold-ups because of people asking if this is the right bus to So-and-so and then being told no, and having to have explained to them where to catch the right bus - but hey. It's a bus, not a Ferrari, so you're not going to get anywhere very fast.

Point being (sorry, there was a point to this), I still am a bit concerned about the loss of cash as a "payment of last resort" - eg, late-night loss/theft of Oyster card. But obviously my response to their survey wasn't persuasive enough - assuming they actually read any of the responses.