Scooter as in a type of motorcycle with a step through frame: https://en.wikipedia.org/wiki/Scooter_(motorcycle) They are heavy and stable, unlike the standing type.

They may be less dangerous than a bike because they can go quite fast, matching the speed of cars when riding on the road, which helps you avoid dangerous situations in which car drivers try to pass you without enough space to do so. Good bicycle infrastructure can minimize this, though it doesn't seem like Denver has it.