Most vehicles in the world are operated by throttles
Above I've shortened your post to what matters. Those are motor vehicles.
Pedelecs are EAPCs, electric assist pedal cycles. They are not motor vehicles. They are bicycles in law and in fact, so are only intended for those who
CAN cycle any unpowered bicycle on the flat in still air, to assist them when the going gets tougher. EAPCs are
NOT intended for those who cannot cycle an unpowered bike due to infirmity or disability.
But of course if they have throttles and can propel along the road without pedalling, they are no longer bicycles in law, they are motor vehicles in law so become mopeds, having to be registered as motor vehicles.
They who can cycle a little but not adequately enough have another provision in law, the Low Powered Moped class, legally known as L1e-A. They look every bit like pedelecs and also assist the rider, but they can do that more adequately since they are allowed up to 1000 watts rating.
Forget about campaigning for throttles on pedelecs, you are never going to get them, that is an absolute. Instead campaign for sensible changes that might be achieved by easing our laws in other respects. For example:
Allowing the above L1e-A class to be ridden with a throttle at at any age over 14 without a driving licence and only a cycle helmet rather than a motor cycle one. Also allowing their number plate to be the same small one that the S Class enjoy in some countries. Changes of this sort would create a market for them which manufacturers would fill with a suitable range of models, making them popular and expanding the numbers cycling one way or another.
The French are a good example of the easement that can happen. They have exactly the same pedelec law as us, but have easier low end motor vehicle laws. For example the low powered cars limited to 45kph (28mph) known as quadricycles can be driven by anyone over 14, and a driving licence isn't necessary, just a much easier to obtain safety certificate. And they can carry a passenger, not like our rule of no passengers without a full licence.
We already have an example of that easement here. Those low powered cars can be driven here on a group AM moped driving licence without an instructor, the lighter ones even at 16 years old solo instead of the usual minimum car age of 17 with an instructor. So you can see it's not impossible for us to ease motor vehicle law where appropriate, but we will
NOT ease pedelec law, since they have to remain bicycles which are pedalled all the time.
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