I got an e-scooter to ride to work daily, as riding a mountain bicycle in the morning traffic is always a challenge.
I have learnt why some e-scooter users prefer to ride on the road.
I have encountered the following obstacles: narrow pavements, crowded pavements, uneven and wobbly pavements, parts of pavements outside shophouses taken up by merchandise, pavements with barriers such as rubbish bins and lamp posts smack in the middle, pavements with concrete or metal drain covers that make a loud noise when you ride over them, and cars parked on pavements in front of private houses.
I also incur the wrath of unhappy pedestrians when I ring my e-scooter's bell or say "excuse me". Then, there are pedestrians who are "phone zombies" or hold conversations in the middle of the pavement, and dog walkers waiting for the animals to answer nature's call.
The only time I have an easy ride is late at night. Even then, I have to be mindful not to go over drain covers.