> Carrefour has stores in Italy and Spain.

And Auchan has stores in Spain (Alcampo).

I'm not saying that the boundary is a 20km high wall of fire nothing can go through.

I'm saying that:

1. the direction is mostly big countries -> smaller countries, and very rarely big countries -> other big countries or even rarer, smaller countries -> big countries.

2. 20+ years after the EU has started, the level of high level integration is still pitiful.