I’m not defending the system, just explaining how it works as far as I’m aware, and it’s nothing to do with Monzo. When an ATM recognises a card as a domestic UK debit, it doesn’t present a language choice, it just uses English. And even the language choice provided for ‘foreign’ cards is not about an inclusive society, it’s about appealing to tourists. Otherwise why would it only offer French, Spanish, and German. If the ATMs were trying to be inclusive, there are various other languages which should be offered, based on UK demographics.
None of this is really relevant to Monzo, it is part of a different discussion entirely. The question here (and for Monzo) is: should Monzo cards be recognised as UK debit cards. I can’t see a good reason they shouldn’t be, and it causes confusion if they’re not (cf. the ‘your card issuer may charge you’ message). As far as Monzo’s future roll-out into other countries, it’s up to them how they handle it. But I would think that if launching in, for instance, France, they would want the cards issued there to be recognised as domestic French debit cards.