Alignment is a mechanism to prevent beggar-thy-neighbour policies that lead to a race to the bottom, with everybody worse off. If you have a porous border witho

Alignment is a mechanism to prevent beggar-thy-neighbour policies that lead to a race to the bottom, with everybody worse off. If you have a porous border without alignment, you get smuggling. The EU single market is a definitional concept, it exists by definition. Not all goods and services are in the single market, but the scope gradually increases over time. Necessarily, as the scope increases, the need for harmonization increases, and that's what often leads to accusations of loss of sovereignty.