When driving through a toll both with a transponder, it is common to have some form of display feedback to the driver. For example, the US state of Maryland has an explanation here showing the three key components of the system (from a user perspective), including #3, the Driver Feedback Display.
Apparently, the US state of Pennsylvania used to have such indicators, but removed them in 2017, and now drivers going through an equipped tollbooth have no way of knowing whether or not the read was successful without going online to check their account a sufficient number of days later to allow time for the read to post, or phoning the turnpike authority.
This seems like a pretty bad UX decision. Yet it was intentionally made, reportedly "due to a change in federal guidelines." The change in guidelines also seems to have been intentionally made for some reason or set of reasons. What are those reasons? Why is this change considered a good thing to expend time/money/effort on?
Hypothesis: This change could impact speeds at tollbooths. For example, if a tollbooth is signed 5mph, and a driver is approaching it at 10 but sees the light acknowledging their tag was read, the driver may just continue through without slowing down further. In the new condition without the lights, drivers may be more likely to slow down more and go through at a crawl to try to increase the probability of a successful read (assuming higher fines for read failures, as is often the case). Any studies about that are welcome in answers.
This would seem likely to increase congestion around tolls and increase environmental costs of tolls, but speed enforcement at 5mph tolls may be a public policy goal, to promote strict rule-following in general. (Is that the reason?)