When they come in direct from China that is bypassed because so much stuff goes unchecked at customs. Unfortunately, a lot of the "UK" sellers are based in China, so difficult, if not impossible to enforce upon them. Mention it to genuine UK sellers and they act shocked and "don't realise"!!!
Another dodgy area is 13A plugs in the UK. Some items don't need to be earthed, so a plastic earth pin is acceptable. Class 1 appliances must be earthed and plugs must comply with BS1363. This means the earth pin should be completely metal. Some cheap plugs/ pc leads come with a earth pin with plastic at the top totally illegal!! Finally, I have purchased items with a dummy UK plug which looks identical to a real one, but.... There is no fuse holder inside!!!
Lets be careful out there folks. The World is easier to trade with these days, but safety standards are universal!!!