Since tollbooths can scan license plate numbers, why is it necessary to have an EZ Pass transponder?

I had been reluctant to use EZ Pass. It is just another complication in life that can go wrong, and the use of EZ Pass by others has reduced the traffic at cash paying tollbooths to the extent that there is not that much advantage in using EZ Pass. Then the state announced that it was going to start charging more for those who pay cash.

I was curious to know how the device works and found out that the transponders contain a non-replaceable lithium battery, which they don’t tell you about. Then I wondered what happens when this battery, which lasts 5 to 7 years and which many drivers do not even know they have, runs out. According to what I was able to find on the Web, they charge you for the toll but do not charge a fine. If they can charge for a toll without the transponder, why bother having a transponder in the first place?