Do we? Transporters are magic. They've never been logically consistent. Half the episodes either would have resolved in 5 minutes or never happened if they were.
My headcanon is that they have feedstocks and are just teleporting atoms around and gluing them together, maybe adding and electron here and there. If anything it's the most consistent use of their transporters.
Not only. I live in Norway, where pedestrians have right of way and drivers are extremely careful. Discounting the risk from cars, there's still more personal danger to users of scooters as opposed to cars. If you have an accident on a scooter, you'll get scrapes, bruises, broken bones. As compared to a car, where unless you've really screwed up, you're unlikely to take any injuries at all.