This does have a minor drawback on the service provider side as allowing people to sign up for a service with direct debit is hard to get right, so many services prefer to offer credit card payment even if it is more expensive. There is no way for you to verify that a person signing up is actually the account holder save for doing the "we debited 1c on your account" thing, which takes a few days.
Yes, and that's arguably by design. If you need confirmation of funds, cardholder/accountholder authentication, and a dispute mechanism that doesn't side with the customer in 100% of scenarios, SEPA Direct Debit is probably not the payment method you want.
> the "we debited 1c on your account" thing
This doesn't actually work with SEPA Direct Debits, since there is no such thing as "disputing a reversal" or "compelling evidence": If the accountholder says "funds back, please", the involved banks have to oblige.
In fact, direct debits are so reversible/non-final that it's SOP for bankruptcy managers to claw back all of the last 8 weeks' worth of direct debits drawn on a bankrupt person's or entity's account, which can be quite surprising for debtors.
In other words, it's possibly a better mental model to think of direct debits as a request for a wire in 8 weeks that gets earmarked for approval by default if enough funds are present, but that accountholders can cancel at any point in time, as far as finality (but not liquidity) is concerned.
The main problem is that if the service provider has no proof that they legitimately had a contract signature, the account holder can reverse the transaction for much longer.
