The debit card number is a layer of abstraction that allows you to HIDE your bank account number from retailers. If you give someone your bank account number they can do whatever they want until you shut down that BANK account.
Someone steals your debit card or the number it's super simple to get that changed and replaced. Someone steals your bank account number it's a nightmare.
If bank account numbers were as high risk as you say, we'd hear about rampant scams where waiters and cashiers at stores jotted the numbers down when you paid with a check and then drained your bank account later. That dog would have barked.
So account numbers are essentially secret?
Over here, they're like phone numbers. You need them to transfer money to someone else.
Does that mean you should NEVER pay anyone by cheque since it has your account number printed on it?
Why is the USA one of the only first-world countries that have such prevalent usage of cheques, but it's seen as so dangerous to disclose a bank account number?
What can someone do with just a bank account number, and why isn't that problem being fixed?
The USA is far behind on banking security. We're still using PIN numbers for debit cards and you could take my credit card and sign for any charges on it. A lot of people in the USA sign "CHECK ID" in the signature panel of their credit cards in an attempt to stop this. The idea is that if it says CHECK ID the clerk will definitely stop and check ID. But if it's not signed (which they aren's supposed to accept) or the signature is incorrect.. a store clerk will 99% of the time just pass it on. I actually never sign my credit cards because it requires a damned marker that won't look like my signature anyway.
I've never once been hassled.
I'm actually thinking about writing a blog post explaining my theory behind why this is the case. Would that be interesting?
tl;dr of my theory: geographic size and decentralized gov't in the US allowed a paper cheque system to outlive other countries'