Direct debit is the UK name for what I think are generally called Automated Bank Drafts (edit: automated clearing house/ach) in the US. (Apols if different in canada, not at all familiar with that jurisdiction.) fundamental problem with DD for POS is that if set up on the same day it's not pulled for a while, and can take up to a week to arrive - it's typically used for paying utilities and the like, regular bills sort of thing, or subscriptions (although that's changing now).
In Canada we have both the traditional direct debit (where you provide online or written authority to a company to deposit/withdraw directly), but also Interac Direct Payment, which I suppose is network similar to Maestro or Girocard, except all/most payments clear same-day, since it was an extension of the ATM network and PIN pads were installed across every merchant in the country.
I believe the vast majority of retail transactions in Canada use Interact Direct Payment (over physical cash or credit cards).
