I think this is slightly more challenging, as the debit card scan is just using image recognition to pre-populate some of the fields. What @chistery is suggesting would require Monzo to have a database of merchant payment details and then match them. So, the image recognition would be used to pull the long number off the credit card, but the ‘difficult’ part is then matching the PAN to an issuer and having the payment details of the issuer. Or recognising the Thames Water logo and then having all the payment details for Thames Water on file, and also knowing and recognising the reference required for the payment.
I think it’s this underlying database of merchant payment details that will take the work, and needs to be done by Monzo. It’s fine to use crowdsourced data for logos and location on transaction details, but when looking at payments, you have to know that the details are correct before sending the payments. So it could use crowdsourcing for submission, but a high level of verification is needed on the Monzo end, and then the details need to be ‘locked’. I agree, though, that this is a feature (in basic form) that legacy banks have, and would be even more useful on smartphone banking.