That is easily circumvented by those who wish to. It is ripe for exploitation.

Only on a small scale, and that happens now and always has.

While my main objection to most of the proposals around the Irish border is to ensure we do not recreate the Troubles, I also have no wish to incentivise criminal activity along the border. Things are 'small scale' precisely because the regulations are and have always been sufficiently similar so the profit opportunities are small. The greater the difference in regulation or taxation, the greater the potential profit and so the greater the attractiveness to the criminal mind.

Remember a border is not just about taxation. It is also about such things as fake goods and keeping out 'the bad guy'. So any scheme that neglects that second aspect is inherently flawed. Number plate recognition, for example, can spot which vehicles were where and when, but tells you nothing about who or what was in them.