fuck this makes me angry!
"No banking details have been taken that you wouldn't already be sharing when you write a cheque or give to someone so they can pay money into your account."
A few years ago, we rather foolishly left our account details on our website for people to pay us, and we had a dozen or so direct debits set up through our account. Scammers can use these details to order services, sell them to their marks, and then run off with the cash, whilst the mark realises a few days later that the service was never paid for.
No checks are done when setting up direct debits.