In a simple layout shop would the customer WC doors opening onto the customer area and the staff area doors require quick release thumbturn mechanisms on the inside of the door or would key lockable devices be acceptable if the key remains in the door?

Being of a certain age I use them regularly and most if not all they use a self locking deadlock on the outside and a thumbturn mechanisms on the inside which would be acceptable in an FRA. What I do find is most persons on the till get fed up issuing the key or customers leave to door open.