That's not true. These rating are in fact the law and no store can sell a Mature game to anyone under the age of 17. This isn't anything new either. This has been the law for a while. That's why kids always have to have their parents buy certain games for them. That is also why the Xbox regulates between children and advlt accounts. Because they legally cannot sell Mature rated content to minors.
Nope. That's like saying a 3 year old could buy a pormo. The ratings aren't suggestions, they're mandated and official.
Okey, i just checked it up, We use PEGI here in Sweden, from what i can gather its the law in the UK (since 2012 july 23'rd) but NOT here in Sweden, so for us its just a recommendation.
(Out of the 34 countries that use PEGI 8 has it legally enforced

)