This is the first I've heard of people tampering with the brake systems - it's incredibly malicious. I understand some people might be frustrated by the scooters, but is manslaughter really the right way to go about it?
...or do those even exist outside of America (and maybe the ex-Commonwealth)?
According to French rules of the road, that is. https://ressources-ergo.com/legislation-et-fauteuil-roulant-...
https://www.gov.uk/mobility-scooters-and-powered-wheelchairs...
Do these even exist? I walk faster than 4mph and I'm routinely overtaken by these scooters on the pavement. I've never caught up to one.
FWIW the only things allowed on bike lanes are bicycles[0] and tricycles. Motorised cycles (including e-scooters or ebikes) are not allowed and should be on the road (if they're legal at all, which e-scooters often are not as they don't fit the motorbike standards e.g. no license plates, etc…).
[0] this includes EN15194 LEV: pedal-assistance only, under 250W continuous rated power, 25km/h assistance cutoff
To the extent that anything not obviously / actually a bicycle and not covered by EN15194 (mandating that pedelecs be legally considered bicycles) is left entirely to each country's devices, yes: the stuff above is french law (current as of now, a law passed early this year to make e-scooters legal under various constraints from September).
Other jurisdiction could have other laws / criteria yielding different results e.g. I think in Switzerland s-pedelec (faster and throttle-activated) can and must use bike lanes, but are limited to pure pedalling in pedestrian zone. Apparently your jurisdiction is based around speed capabilities, IIRC Belgium is similar, if devices can't go above a certain speed they're treated the same as bicycles.
For that matter you can easily achieve 25 km/h on a normal unpowered bike. They don't seem to kill as many people as motorcycles though.
You'll know right away if the cable is cut--before you even start your ride.