In Brazil, you can enable the same card you use to manage your bank account and withdraw cash as a Visa/Mastercard credit card. So every time you make a purchase you get a prompt like this

1. CREDITO

2. DEBITO

where you choose if you want to pay with credit or debit.

Last year I went to the UK on vacation. While paying my bills I noticed most people wouldn't know what to do when prompted. They would look confused and just hand me the card machine and let me handle it.

A good amount of places also ask this in the US.

In NZ if you just type your pin it selects the default account which is your every day banking account.

Same thing in Singapore. Never need to select credit in NZ / Aus / SG. Unless you specifically want to use credit.

Since last Thursday they are legally required to ask you but if it's anything like Germany most merchants don't care.

When I use my card outside the UK in a country where this is the norm (e.g. Italy) I am asked to choose the 'circuit' before paying, but the only choice I am given is "VISA DEBIT" - this is on ATMs and Chip&PIN machines.

I don't think any UK banks have their own payment network. The cards you get to access the account directly are debit cards (usually Visa Debit or Maestro), some (i.e. children accounts) give you a 'cash card' which only works at that bank's ATMs.