That would just create a diplomatic row with FranceGet a decent number of UK official looking high speed boats . Put planks across the front
Push the boats back to the French coast, decant the occupants and destroy the boat.
WHile the politicians are arguing about it being illegal, the people wouldn't risk losing their money, so the practice would stop
France would then retaliate, probably would close the Calais customs….not great given the value of trade that passes through.
It’s easy to come up with these simplistic arguments…not so easy when you add up the consequences.