Then you have the opposite problem. Customers are shy about giving out their bank routing info if large transactions aren't reversible. You don't want it withdrawing against the full balance of your bank account.
It has to be something that puts a reasonable amount of the risk on the user, rather than either none or an unlimited amount.
All of those services accept credit cards. Because there would otherwise be too many people unwilling to give up their bank routing number.
What you need is something that has irreversible transactions but also has a monthly total transfer limit and a "routing number" which is unique to the merchant and can be revoked for further transactions at any time. Ideally also something that allows people to make purchases on credit and earn "points" so it's competitive with credit cards.
That way people would actually be willing to use it, instead of having to give a startup with no reputation (or a company with the foul reputation the likes of PayPal) access to their entire bank balance.
> All of those services accept credit cards. Because there would otherwise be too many people unwilling to give up their bank routing number.
That's not actually true, they allow both ACH and debit cards.
But either way it's irrelevant, revocation risk can simply be offset with a fee.
The system doesn't suddenly stop working if you can only pass on 95% of the deposited amount. Or even 90%. Or 80%. If people want it, they'll use it anyways. The thing is they don't.
It has to be something that puts a reasonable amount of the risk on the user, rather than either none or an unlimited amount.