Why is 30km/h cutting edge speed for a 5 year old

lets see in germany

Just use a car and get a ab license to succeed. Nope

Use a moped and a am license. Nope

No easy option for the 5 year old

The option the 5 yo has is:

Walking

Bicycle

Shooter

Tricycle

None are electrical or motorised.

So 5 yo has to get a bicycle and just pedal fast.

Thats the theory lesson