I think when it comes to safety restrictions should be there. The hacker in me hates it too but just imagine if a small portion of standard-looking outlets did not output 220V (or whatever standard you have) and say 330V.
Many applicances would break, or perhaps even catch fire.
If there were many different USB-A devices and people were used to checking the voltage output before plugging, that might not be needed, but since probably none of us check for a USB-A port to see if it outputs 7.5V, it better be mandatory to be certified.
Though, maybe it is, but still those cheap Chinese adapters slip away.
Many applicances would break, or perhaps even catch fire.
If there were many different USB-A devices and people were used to checking the voltage output before plugging, that might not be needed, but since probably none of us check for a USB-A port to see if it outputs 7.5V, it better be mandatory to be certified.
Though, maybe it is, but still those cheap Chinese adapters slip away.