The design
The tiller is the steering column. The console on top holds the speed dial, battery gauge, horn, lights, and key, in your sightline instead of down by your feet. The throttle is a lever: one way to go, the other to reverse.
The shared machine
Same bones. Different answers.
Every scooter in the shop is a tiller, a swivel seat, a battery, and a rear drive that brakes when you let go. The types are not different inventions. They answer four questions differently: how tight the turn is, what the ground is like, whether you can lift it, and how long the day is.
The result
Let go and the electromagnetic brake comes on. A mobility scooter stops when you release the lever. It does not coast. That single behavior is why the controls live in your hands, not under a foot pedal.