Geofencing will work for things like shopping malls but is unlikely to work for individual roads, particularly like the A19 as it has residential roads and separate cycle paths running alongside it in many places along with roads running over/under it in many others.
To me the issue in the UK isn't the tech but it's application. Early results from the trial show some underage users, some riders riding inappropriately, some being used in inappropriate places (derestricted dual carriageways, pedestrian malls, footpaths) with zero enforcement. The issues are some of the users, the weakness of the laws and the absence of law enforcement. To be fair the same area suffers from similar problems with illegally driven off-road motorcycles although the Police attempt to catch those (generally through "intelligence" as their X5s are incapable off-road).
Chalk up another failure of central government, both the Politicians and the Civil Servants.
I've been in touch with our local MP (who I didn't vote for) and apparently he's receiving a large amount of negative correspondence about them and we are not even in a trial area. Unless things improve the trial may not result in e-scooters being allowed permenantly.