is that the DPS, CHP, LSMFT, FBI, BSA, whatever - each has their own interpretation of the law, even down to the individual officer. Lots of horror stories here from racers and the Texas DPS on getting hassled. The down side is that the officer on scene can write you up for what he thinks is wrong, then you get to sort it out in front of a judge. A total waste of yours and the courts - and the taxpayers - time.
I need to go Googling and see if that case from MI or OH (forget) was resolved - where a guy pulling a box with his show car and the highway patrol wrote him up for a $750 ticket as being a commercial hauler. No name on the trailer, no stickers on the car.
Have also heard of people being hassled because all fuel has to be hauled in DOT approved containers. Regular race fuel jugs from VP apparently are not DOT approved. And neither is a fuel cell.
As much as I loathe gubbermint interference, this is one area that could really use a good, hard and fast set of overall regs rather than a mis-mash of state hacks.