These systems are a mess. The system in TX seems particularly poor for rental car users. According to instructions when I called the Houston customer service they told me I needed to do a plate based registration when I had the rental car and I could not use a sticker in a rental car. I asked why and was told the stickers are not transferable from car to car. I looked on the app where I registered it to my personal vehicle to get the sticker sent to me, and saw there is an option to change vehicle. Finally the rep told me the reason you can't transfer the sticker is because moving it from car to car may "damage" it. When I said I think I can just tape it to the window or not fully stick it on, the rep sighed and basically said that should probably work but I cannot add/remove a vehicle on my own on the app I need to call them when I arrive and call again when I leave. I mentioned there looked to be a way to do this on the app and the rep just said okay you can try that feature... then said if there are any billing discrepancies I will have to work it out with the rental car company. I don't understand why they try to discourage the process I followed, I feel like it just makes it hard for rental car users unnecessarily. So I ordered a Houston sticker and stick it in the window of rental cars leaving a bit of paper on it so it isn't 100% stuck so I can move it from vehicle to vehicle. Fortunately I have had no issues with overcharges and all tolls have been properly billed to me with this sticker.

The IL system with a plastic transponder box is much better. It is very easy to just move that from car to car and it works fine. You just have the app and you register the vehicle you're driving. Very easy. Of course you have to pay for the transponder but the tolls at the lower rate quickly cover that cost.