Maybe I'm missing something, but Germany's personal car toll system was supposed to be offset by a rebate on car taxes that would benefit any resident (or more precisely: anybody paying their car taxes in Germany) and was found to be in violation of EU regulations. Are there special cases for tax rebates or what would have been the difference?

It is my understanding that this ability to discriminate only applies to acts by the state but not to commerce.

Perhaps this could be workable by issuing all residents a license to buy? Restriction in buying items certainly exist: guns, alcohol, etc