Your understanding is hazy (as ever). The backstop is no more than a proposal at the moment and is not in any way in force. It's to do with our leaving with a deal, nothing else. The backstop keeps Northern Ireland in the customs union in the event of the lack of a trade agreement with the EU. It comes into force only if we can't strike a trade deal at the end of the transition period. We get a transition period only if we leave with a deal, not otherwise. Do feel free to ask any of us, bar Iains, for further explanation.