I'd say the opposite, intra-EU trade is more like international trade, at least for B2C. Each country has its own national market situation, companies cannot easily expand to the entire EU because in every EU country they will find different local competitors who know the local market much better than they do. Every product has to be localised for the local language and culture. All marketing has to be localised.
Despite efforts to the contrary the EU functions as a glorified free trade zone, half a century of integration cannot beat 1000 years of fragmentation.
