Rental scooters are allowed to use up to 500W motors and weigh up to 55kg, so they're going to be electronically limited to 15.5 mph, nothing said about their acceleration profile. How long before someone posts a YouTube hack or even worse an app to just unlock the limiter?
Current limits on e-bikes are 250W output (you can buy 500W+ motors but they are (poorly) restricted).
Look at how dockless bike hire has gone, first a load of littering then you barely see them now
External Link/Members OnlyAnd the chaos of scooter hire companies around the World.
Perhaps these new ones will be managed a bit better because the kit is significantly more expensive but the chances are that any dockless ones will simply be vandalised by those who can't afford (the deposit) to ride them.
Deaf and Blind charities have been unimpressed and are fearful of these heavy, fast, recklessly ridden (because they will be) machines being a serious hazard to their constituents.
Initial trial may require riders to have (provisional) driving licences but they aren't required to wear a helmet. Anyone with a licence is going to be 50+ kgs so being hit by 100+ kgs of twat doing 15+ mph isn't going to be pleasant for the pedestrian, don't give a stuff about the twat, hopefully Darwin will take care of it.
Average London journey speed is <10mph so no reason for the scooters to do anything more than 10 mph.