Our laws don't permit a child to drive a car on the road - the consequences of making a childish mistake controlling a vehicle of that weight and potential speed being too dreadful for society to permit.
Given that bicycles weigh little, and that children riding will struggle to reach 15 mph, let alone 20 mph, it seems reasonable that they are allowed to ride bikes to get around as they're very unlikely to cause injury to another person..
It's illegal for them to cycle on the pavement adjoining the road so they're not likely to bruise or topple grannies.
And it's legal for them to cycle on the road where they're unlikely to damage or kill other road users.
So the only reason that we see so few kids cycling on the streets to school, to the shops, to their friends' houses must be that other road users, the adults who drive around, and the adults that make up the rules, don't make the children welcome on the roads.
Some may say that this is entirely fair. After all, children don't pay road tax (or council tax and income tax for that matter). So they shouldn't have any right to use the road (plus they're probably not doing anything of economic value like delivering horse meat to Tesco). But let's ignore those people who believe that a public resource should only be used by those who are required to pay tax, and that commercial use of space is the only valid use,
Let's consider the way that our society expects the child, as they engage with crushing tons of metal, to deliver an adult level of consistent cycling, mature decision making, assertiveness and communication.
For example, two road users, each one coming from a different direction, arrive from side roads at a cross roads where they must give way. The first part of the decision making is childishly easy. There are 'Give Way' lines. So wait until there's a suitable space on the major road before making your move. But, hang on, who will go first between you and the person opposite?
Is it law that the motorist must let the cyclist, who may be a child, go first? That would be a straightforward thing to teach a child.
It's not. The Instructor course for the National Standard for Cycle Training, describes what the child needs to do:
Trainees should seek eye contact with drivers of vehicles that may emerge from the side road ahead that they intend to ride into. The Highway Code does not contain clear guidance on who has priority so the trainee must communicate effectively so the driver knows who is going first.
I wonder if the Dutch manual for cycle trainers about cross roads contains similar advice?