All of the NTTA-operated toll roads scan your TollTag, if present, and pull your plate from the flash photography. If a TollTag is present, the TollTag is charged -- even if the plate is associated with a different TollTag (and that TollTag isn't in the vehicle) or not associated with any TollTag in the NTTA system. So you 100% should have pulled your own TollTag from your vehicle and saved $65 in bullshit administrative fees.
As an aside, the entire concept of toll roads is abhorrent. Why would anyone think that privatizing transportation and road infrastructure is/was a good idea? It's a horrible idea. For the most part, the NTTA toll roads are built in affluent areas of the metroplex. It's clear that infrastructure improvements are necessary and, instead of allocating state and federal highway funds and, you know, responsibly spending our tax dollars, they continually enable NTTA to operate and expand their money mints.
It reminds me of a toll bridge built decades ago. The toll bridge crossed a sprawling lake and provided a desperately-needed interconnect between the two sides of the lake. Before the bridge, you had to circumnavigate the entire damn lake to get to the other side. When they sold the project to the general public via a bond vote, they said that the toll would apply until the bridge was paid off in full. However, once they realized the volume of vehicles taking the bridge every day to shave 20-30 minutes from their commute, they reneged. It's been a profit-generating toll bridge ever since. Bullshit.
And yea, I pay between $200-300/month in NTTA tolls between the DNT and the Express Lanes to/from DFW. Call me bitter.