The definition of "legal" is teh main thing
but the average member of the public knows little about it
and even the ones who have some fair idea can;t always tell
but, as always, the people that are doing things that affect you badly are the ones you remember
so if I tootle down the High Street - which is pedestrianised - on my bike
at a slow speed - just over walking speed - and stop frequently to make way for people walking
and take a route that produces the least possible affect to people walking and pushing pushchairs etc etc
then I am breaking the law - technically - but not causing any problem to anyone
and I will probably not be remembered by anyone
but one person whizzes up on a bike with a 1000W motor and a battery nailed to the frame and help on by Gaffa tape
then they will remember that "all ebikes" go whizzing up the High Street making people jump out of the way
which is why the media need to use a different term if something happens to a legal one than they use for an unlicensed electric motorbike/moped
e.g.
for example you might see the following is a boy if killed by someone doing 50 on a SurRon type thing
"boy killed by ebike on High Street"
and then if some old codger on CyleChat is killed while riding responsibly and is hit by a car where the driver on on they phone
"Man on ebike killed on High Street"