The pre-pay card I have is free - no charges except for ATM withdrawals, and I never use it for that.
Agree about the DD thing and the amount of credit people build up over the summer, many hundreds of £s. One million customers with £200 in credit is a tidy sum, hence my tactic. Water is on my card as well.
It might take an hour or so to set these things up but once they are done they are done. Your weekly / fortnightly / monthly amounts are always the same so it makes it easy to budget. The balance on the card goes up and down as bills get paid so the bills always get paid.