This post makes no sense, the EU doesn't have any rights of interior taxation, the member states haven't devolved that. It only does trade agreements and sets

This post makes no sense, the EU doesn't have any rights of interior taxation, the member states haven't devolved that. It only does trade agreements and sets (not: collects!) import/export taxes. The only thing this could be is somehow summing/estimating from member states' numbers? Very unclear to me what is going on here. I'm treating it as bogus for the time being. Can somebody else make sense of it?