I don't think there is a rationale; they just haven't updated the law recently. In their defence, they do also have things like Brexit to worry about.

Apparently it is currently unclear even whether and where roller skates are legal, and it is occasionally claimed that wheeled bins are technically illegal on pavements, even though they are provided by local authorities and people are expected to put them in front of their houses on bin days.

Of course, it's unlikely you'll be stopped by the police for using an electric scooter in a considerate way. But the lack of official approval is bound to prevent widespread use.

Meanwhile, feral youths, without helmets, ride unlicensed, uninsured pit bikes across roads, pavements and other people's private land and the police have no resources to do anything about it. On the other hand, a middle-class middle-aged gentleman on a scooter would be much easier to catch, so do be a bit careful if you decide to defy the law. If you see the cops coming, run for it. They almost certainly won't shoot you.

As far as I can tell, it's not so much a ban as that the current legislation just doesn't fit them. They don't fit into the existing category of "electrically assisted pedal cycle" and they don't meet the requirements of road vehicles.

Legislation needs to catch up. There is a European effort underway to create safety requirements and test methods for Personal Light Electric Vehicles that would seem like a good start [1]. Maybe we'll leave the EU just in time to not get the benefit :)

[1] https://www.din.de/en/getting-involved/standards-committees/...

None, it's not a deliberate ban, it's simply not listed as allowed because no one considered it when the law was created and no one has bothered to (or was able to) change it.

I believe it's the same law [1] that also meant the Hoverboards from a few years ago were also illegal to ride on public pavements and roads[2].

[1] http://www.legislation.gov.uk/ukpga/Will4/5-6/50/section/72

[2] https://www.theguardian.com/uk-news/2015/oct/12/uk-hoverboar...

Here is an article though it gives no rationale. I think ebikes are allowed on roads as they are pedal assisted. Bikes that don't require you to pedal are in a grey area. Since eScotters have no pedals they are not legal on the roads http://news.bbc.co.uk/1/hi/magazine/5271874.stm

Chances are they're simply not covered by existing rules and those rules work like a whitelist.

Basically "we don't want to be accused of not protecting people from their own stupidity"

When you talk about electric bikes and scooters the picture formed in the heads of the people who run nanny-states looks a lot like mopeds in Dehli.

Security, I guess.