Competitive salaries under the sun

I ended up on a new Spanish IT jobs board and I started clicking on some offers, out of curiosity. There was something peculiar about it all: each job description roughly started with a very topical and unsurprising "work in sunny $SPANISH_CITY", but then failed to provide the estimated salary range the company would pay you for actually staying inside an office instead of enjoying the shiny outside sun. Not even a maximum cap--just a "competitive salary" mention. Do they mean you have to compete with the rest of candidates?

In contrast, most offers in the UK have the salary range already in the job title, as in: Software Engineer, 35K-50K, so you just don't even bother clicking on a lowly paid job... unless the title is wildly intriguing, of course!

Why is this so?