Italy has a fraction of the territory of Spain, of which a fraction is usable in agriculture (Italy is mostly mountains), and a fraction of that can be used for Olive trees. Of course Spain has more yield, with their immense spaces and flat fields.
As for selling more or less, it's just a supply chain thing, Italian companies were better placed to sell it, but the bottle clearly states when it's Italian oil and when it's not.
These sort of antagonizing takes intra-EU are not helpful.
Idk, we've got Ferragosto for example as a national holiday where EVERYTHING is closed..