Why is Spain so corrupt?
Because it has an over sized and over complex government system which is too hard to impliment properly, too easy to avoid, and itself corrupt.
I will give a personal example: when we sold our last flat (last year) the (Spanish) purchaser was happy to declare the full purchase price to Hacienda. Conclusion – there are Spanish people out there prepared to play by the rules.
We were buying as well and we also declared the full purchase price to Hacienda. However we purchased our flat at a price that was below the valuation Hacienda gave for our flat. This left us with the choice of either declaring the real amount we paid or declaring Hacienda’s higher valuation (and therefore paying more tax). If we declared the real purchase price we would have faced the risk of being fined by Hacienda for paying with black money, because it is inconceivable to Hacienda that anybody could genuinely pay less for a flat than what they value it at (a friend did try it once when he bought a cheap flat in Zamora, and he was indeed fined). So we ended up declaring Hacienda’s price and paying additional “tax” that we shouldn’t have.
When you combine examples like this with other experiences of trying to deal with the Spanish state (and also with service companies that are linked to the Spanish state) then you realise that by dealing with them you are left vulnerable to being extorted.
This has nothing to do with corrupt politicians, etc (although they don’t help) or the fact that those employed by the state have their jobs guaranteed at your expense (I fully expect Spanish pensions to be raided any week now in order to keep paying funcionarios). It’s just that most people who live and work in Spain realise that whenever they deal with the Spanish state in an open way the state will see it as an opportunity to take as much money off them as it possible can. So many simply choose not to.