[justsomehnguy]

> Because people like the assurance of a check, or a receipt, or a payment confirmation

What is more assuring then the actual payment itself, transferred to you just as you talk?

> How do you initiate a wire transfer? [...] -- their bank and account number, for starters

Ugh, 21st century says hi.

Just a mobile number, some provider independent number, like SEPA [0] or in some circumstances just the plain plastic card number, be it a debit or a credit one.

> Sure you could do it on a mobile device but seems a lot more time consuming than writing a check

Scribbling something on the paper and taking it to the ATM/bank (or use said mobile to "online check it", oh irony) is sure to take more time than punching in some number in mobile or web app and actually transferring money.

[0] https://en.wikipedia.org/wiki/Single_Euro_Payments_Area