So, if they're able to provide this service, why can't my bank?
I understand that they will only accept cheques from certain sources, i.e. not personal cheques, only big companies. They can therefore be pretty sure that they won't bounce. The risk doesn't seem so high, though I guess there is still some element of this.
This sort of business does seem to be booming though. They also seem to do those cash till payday postdated cheque loans at the rather exorbitant rates, as well as pawnbroking, and various other rather expensive 'financial services'. The market must be there though, but I don't really get why people can't be a little more shrewd about these things?