If you're wondering because Spain is southerly and hence closer to the Equator, consider this: the extreme southernmost point of continental Spain (latitude 36° N) is still farther north than most of North Carolina in the USA [0].

Only the Canary Islands have comparable latitudes to Cape Canaveral. While on the one hand a Canarian launch site could perhaps be a huge economic and productive boon for the Islands, I think that it might conflict with their unique ecosystems, tourism, and even (maybe?) with their current use as a base for telescopes, which is useful thanks to their high mountains and low pollution.

[0] https://en.wikipedia.org/wiki/36th_parallel_north

I wonder if its because (1) theres no space left on the Med coast in Spain for this or (2) if a Spanish launch site does not offer enough angle for moderately inclined orbits because (3) they would still be dropping hardware on central Europe for nearly all common orbit profiles.