There wasn't a mandate - the EU asked the manufactures to adopt a standard "or else we'll look at regulating it", and that worked great, everyone adopted microUSB and then switched to USB-C just fine. Except Apple. And since Apple continually refused to get in line, we're now getting that "or else". Apple is who got the whole industry in this situation.
hilarious that the people in favor can't even agree on the previous state of things... they just get high on "doing something" and forcing compliance - when in reality they've done nothing and have no concept of what creates innovation and progress