Where I live in USA, 25kph is equivalent to 18mph, and almost fast enough to match typical car speeds on neighborhood roads. But I wouldn't want to go much faster because unlike bikes, scooters are inherently unstable.
I don't ride a bike much any more bc of back pain, bit I do use a scooter with no pedal assist, and even at 500W it slows to about 10 mph going up 15° hills right outside my front door.
I'm no engineer, but in the cold weather, the scooter is even less powerful.
I like being able to avoid using a car for most trips, but I could not do that with a bike bc of the pain, and 250 W cannot get me up hills w/o pedal assist.
In hindsight I should have testridden more scooters and foynd one with ergonomics that allowed riding it more like a kick scooter. My current one has the battery under the deck which is great for center of gravity, but makes it dangerous to kick-push.