CE approval is not only a rubber stamp, it's a rubber stamp you get to apply yourself. By applying the CE mark you a certifying that your product fulfils all the necessary requirements and that you can document it, but no one will actually check. While it is illegal to apply the CE mark to a non-conforming product (or to sell or import non-conforming products with the CE mark), basically nobody gets prosecuted.
Firstly, CE is not a certification, it just means that the product is in compliance with legislation. It's something the companies need to verify themselves.
That leads to the problem child which is China and its lacking morals. Chinese companies will just slap the CE on anything, because the EU say that must and Europeans seems to enjoy seeing it. Sometimes, they will slap on a different CE marking, meaning "China Export". You can tell the difference by tracing the C to a full circle, if that hits the E exactly, its CE as in "conformité européenne", if it doesn't, it's China Export.
If you're a fly by night USB charger manufacturer, you just invent a new brand for next month, so you won't get the fines or be banned.
I've understood the CE marking to mean that according to the manufacturer, the device shouldn't catch fire, shouldn't shock me, and shouldn't give off a lot of radio interference.
Never did I thank that would be some kind of "this is a great thing" approval stamp.
However, it never occurred to me that a USB-A charging brick would be able to give 7.5V, or even 9V or 12V as others have commented. That might completely fry some devices...
Self-attestation is introduced when the industry complains that having a 3rd party verify is too onerous and could hurt business. And they're not wrong, but the result is companies rubber stamp their own compliance. You see it a lot in DoD compliance now, for example.
