For regular bills, when adding a bill pay account online, the bank will ask for your account number... so there must be some way to specify that with an ACH transaction. I've noticed that the custom input memo field visible to the end user goes away on ACH transactions though, at least at my bank. Perhaps it's just used by the account number automatically?
For bills that don't accept ACH bill pay (i.e. most smaller companies and utilities), banks will often print and mail payments via check for free (it just says "signature on file" on the printed check). Like I said, decades behind.
I pay our childminder by bank transfer. Its almost instant to do from my phone, free, and I just put the invoice number in the reference field. The idea that banks would print and post cheques is like something from the era of telegrams. So weirdly anachronistic.
Yep. While Faster Payments is brilliant, BACS' overnight processing and the direct debit system is total sufficient for the vast majority of cases, certainly things like bill payments.