But I thought debit card = bank transfer? There is no protection?
If you have a basic consumer dispute about something (such as a retailer not giving a repair/refund for a faulty item), you should be able to file a chargeback with the card issuer and get a refund.
In the UK, a credit card is much better though, as for any purchase over £100, the card issuer is joinly liable with the retailer for any issues.
https://www.which.co.uk/consumer-rights/regulation/section-7...
In the US, most PIN debit card transfers occur via either MasterCard's Maestro or Visa's Interlink debit networks. Signature debit payments go through MasterCard/Visa's credit card networks. So you've still got the duopoly problem.