Many shaver sockets are designed to take an array of different plugs, they use spring contacts which will not carry much current, but will allow the use of different plugs.
The proper adaptor

has earth connections, and also holds the euro plugs firmer, the two contact version

hold the plug even firmer, there are also versions needing a tool to remove

these are as under UK trading standards suppliers are not permitted to just supply adaptors, it needs to be fixed, but to fit plugs by cutting off EU type it would need training so the adaptor which requires a screw can be fitted by untrained personal but complies with UK trading laws.
These

are dangerous, often no fuse, insulation on the earth pin, and no shutters, but these

supplied to Europe are OK as in Europe they don't have fuses in the plug, OK still no shutters, but you can understand when looking at the two how the error was made and these dangerous plugs have been manufactured.