Reviving old post as it still applies.
Just towed over the I78 bridge from NJ to PA and was charged $18 instead of $3.25. And I made eye contact with the toll taker and said "Class 1"? He just had a blank stare. The electronic sign just said "Paid", so could not tell until my app updated.
I sent a feedback again to the toll authority voicing my issue and said this is bordering on a scam situation as I am sure not everyone knows the correct rates and are being overcharged.

To my surprise they called me today and said "they have been working on this for a while now". By a while, it has to be at least 3 years that I noticed. I asked him how many people are paying this over the years and not knowing to check their statement and your toll rates, he had no comment. He said to take down my tag and pay cash, but then I lose out, as cash charges more.

Since my truck is fine solo, I think it is their height reader that is picking up my trailer and charging me for the larger size vehicle. The rates change for vehicles >8 feet tall, but says nothing about the trailer height, just axles.