Why? Your EAPC must show the power output or the manufacturer of the motor. EIther would prove that your bike was illegal. It must also show the battery voltage or maximum speed of the bike. Further the maximum power output must be 250 watts and it should not be capable of propelling the bicycle more than 15.5mph. The dibble could fairly easily measure all of those things. If your last bike hit 600w in acceleration or hill climbing, it wasn't legal either unless you had it taxed and insured and were wearing a helmet.
There are a few, er, inaccuracies in this post.
The legal limit is 250w 'nominal', but the law realises it cannot defeat the laws of physics, so it accepts such motors will be capable of much higher peak output, typically around 700w.
If there are requirements to stamp the wattage on the motor, such restrictions are routinely ignored.
Bafang are now a major manufacturer of hub and crank motors.
Their 750w hub motor is popular because it's cheap and powerful, but it is unmarked.
The suspicion must be that Bafang deliberately produce the motor in this way to appeal to the European market.
I'm satisfied Bosch have sold me a legal crank motor.
Once again, it is unmarked.
I accept it might be stamped somewhere, but you would have to dismantle the motor to find it.