In reply to Phantom Disliker:
I'm guessing because a one off donation is just that. One off.
One interaction with the donor = 1 donation: not very cost effective
One interaction with the donor = continuous DD donations, very cost effective.
Plus I think it plays on the fact that a large chunk of people will leave a DD in place for a long time because they can't be bothered with ever calling the bank to cancel it.
I 'would' sign up for a charity DD, but I would never feel pressured to do so. If the collector says they're not in a position to take a one off payment then make one directly to the charity via the website.
Edited: Sorry, I misread, I thought this was about a street chugger or a door to door collector, not a tv advert.
Post edited at 13:41