Some country second-level domains cause stupid warnings on badly implemented web forms. I wonder if customer support people have the same crap on the systems t

Some country second-level domains cause stupid warnings on badly implemented web forms. I wonder if customer support people have the same crap on the systems they use, leading them to "fix" the address. It's not unusual for me to type in my email address, and see a validation warning appear below "did you mean xxxx@xxxx.co.uk?" .co.uk is probably the most common, but who would mistype .net.uk, .plc.uk or similar as one of the valid second-level domains?