In motorcycle circles the general accepted “rule†is that the top level of the screen should be at the rider’s nose height. To my experience there is no need to mount screens higher than nose height on a motorcycle - because motorcycles in genera get used for riding on open roads at higher speed.
If the top of the screen is at nose level, rain and wind gets deflected over the top of a helmet at higher speed.
In most countries scooters get used for commuting purposes at lower speed in town. I have no experience with “look through†screens, but I think it make sense to mount these type of high screens if the scooter mainly gets used for commuting in town at lower speed. The high screens will create more wind resistance, but the rider will get more protection against rain and wind.