At many tollbooths in the USA, I have noticed that there is a sign telling drivers not to back up. For example, see this tollbooth plaza on the Dulles Toll Road in Virginia ("CAUTION: DO NOT BACK UP / STAY IN VEHICLE"), or this one at the Baltimore Harbor Tunnel, Baltimore, Maryland ("DO NOT BACK UP").
Why is it important for drivers not to back up out of a tollbooth?
- Is this a safety thing, and backing out of a tollbooth is particularly dangerous?
- Is this a legal thing? (e.g. perhaps cars are considered legally impounded upon reaching the tollbooth and the government requires payment to legally "release" the car, so backing up constitutes an attempt to evade a legal impound).
- Is this mostly a tradition or done for historical reasons?
- Is this done for some other reason?