As you suggest, Transparency!
Local Procedures are in place to stop, where possible! People trying to Buck the system, But! History is full of tales of Buckers! “Tax free cars arriving in the East (not Essex!) with factory fitted installed EXTRAS which No European would order!!
All systems have loopholes, there always seems to be those so minded as to figure out what they are and exploit them.
Coinage and the DM vs. 5p piece springs to mind at the less sophisticated end of the scale with tax fraud via BAOR imports for the more serious minded. The former might have developed to become sawn off shotgun bank robbers and the latter into bankers.