Banks are required to deny bank accounts to people who are disqualified from banking, and also deny them from being added as signatories on shared accounts.
This is why cashless in the UK would be more harmful than in countries where everyone is allowed banking as a right. In the UK, access to banking is a government-controlled privilege, even though most people take it for granted and think that everyone can have it.
https://www.independent.co.uk/news/uk/home-news/home-office-...