Here in the US, nearly all wine stores I've been to sorts wine per type (red, white, etc) for local wines and have a specific foreign section "France", "Australia", etc. Even regular grocery stores tend to do this too.
If groceries chains did this in France, consumers would then rarely buy the Spanish wines unintentionally.
I don't think the winemakers would have a hard time lobbying for at least forcing grocery stores to display foreign wines in a clearly labeled section.