The plugs are part of the overall system they are in and are designed to that. If you have a ring circuit and 240volts like in the UK, then you had better have

The plugs are part of the overall system they are in and are designed to that. If you have a ring circuit and 240volts like in the UK, then you had better have a plug that deals with common failure modes - switches on the sockets, fuses, ground as standard etc. If you have 120volts and a radial circuit then you can perhaps do without it. The US plug does have advantages, like being smaller. UK plugs are really annoyingly large and weighty.