Probably because the strawberries are all being transported abroad by the growers.
When I was over at the beginning of June there were a few stalls at San Pedro and Torreveija market with strawberries on, I bought a kilo but they didn't have a lot of taste so I think they are past the season.
The main fruit crop were Apricots and Cherries (my favourites so I had a kilo or 2 or 3 in my 10 day stay) 
Actually it was 4 but I did give some to my neighbour.
2 euros for a kilo, in the supermarkets here there 1.99 for 1/4 Kilo
I don't think Spain imports a lot of fruit and veg so you'll only find fruit and veg which are in season