Account numbers for the majority of banks use modulus checking to prevent mistakes - not all banks use the same method, so the sort code is used to decide which modulus check calculation to use. There are very limited circumstances in which transpositions can occur and still pass a modulus check.
There are various software products available which take details of all the banks’ modulus check methods and bring this together in one place, such as this one from Experian: What is Bank Wizard
If an organisation wishes to process Direct Debit requests via online sign up, Bacs require them to implement such a system at the point the sort code and account details are keyed.
(Edit - not all banks use modulus checking on their account numbers)
(Edit 2 - this is not the same as Confirmation of Payee)