I have heard this question several times since I arrived in Germany. I am spanish and this question is the following one to the sentence “In Spain, there is a better weather!” Ok, so I am going to try to explain the issue in my view. I did not more special documentation than my own knowledge (I studied Law and I like to read newspapers).
I should add that living abroad thank to my EVS helped me to take distance to reflect on the issue.
Catalonia (or Cataluña in spanish) have been always a prosperous region. Spain is surrounded for the see by many kilometers and as consequence had an efficient trade. The prosperous of Catalonia has been debt to this commerce and the industry that stills nowadays. Catalonia also, for different factors, has the fame to be more open-minded and a cultural and artistic center. On the other hand, Spain has lived a lot of different cultures (arabic, celtic, roman,...), invasions and, of course, wars as a result. That created a mosaic difficult to compose to create the state called Spain.
Anyway, the state of Spain, such we know it today, was born with the political transition and the new Constitution in 1978, after Franco's died (spanish dictator between 1939 and 1975). The Constitution of 1978 still nowadays, with only two small changes to adapt itself to the European Union regulation.
The Constitution of 1978 create a decentralised state with autonomous regions, similar to a federal state but no exactly the same. That autonomy was reached in a slow or quickly way (according to Constitution's rules) in each autonomous regions. Catalonia reached the autonomy for the quick way, considering the independent movement which already existed. In the supreme law was created a solidarity principle too. That means that each region should be solidary with the other regions. That includes budgets and taxes distribution too. And that could mean too that if Catalonia earns more money (always we are speaking of money), should be self-sufficiency or share more. That actually happens because of the high industry of the area. But autonomy does not mean money. The autonomous regions have several competencies. Catalonia even has an own police, Mossos d'Esquadra, very controversial because of the suspects of attacks of human rights, not always good research to control it. The autonomy also means a self-parliament for their own territory. That is the reason because they have too an own president for the region.
Speaking about the president, that is one of the most controversial aspects of the issue and one of the tension's focus between Catalonia and the central state. After the attacks of “integrity” of the spanish State, the Central government applied (not so good as they should do it) the article 155 of the constitution, but with a different solution as the proposed. Because of that, a new electoral process took part in Catalonia with the result of the majority, again, of the pro-independence parties. The formal act of investiture of the president was a problem. The current president was the same as before elections. He was also in a criminal trial in course for felonies of the type of treason and sedition. One of the consequences of criminal law in Spain is the impossibility of taking part of a public charge. That was applied in the case. So, we had a president, who couldn't be a president because of the criminal acts that he made being president too.
Why there is not a dialogue between the Central government and Catalonia's parliament? Although politic ideas are very important, the key is again the Constitution (connected with the political ideas anyway). The Constitution is non-flexible in that point: Spain is one and no-divisible. In any case, the constitutions can change. But the procedure is so hard and costly, that is not an easy decision. In the case of changing the Constitution, it is inevitable to speak about the monarchy. Spain has a constitutional monarchy model, according to the constitution and the history. The problem is the following: there is many people against monarchy who support a change towards a republic. So, the issue of changing the constitution becomes harder and harder.
Should Catalonia be independent? I let it to political ideas. But in fact, I can say, we have actually a living together problem.
I think that is a good example of the multiples questions and conversation that you can take with other volunteers. They ask, you ask and chatting you learn a new point of view. Because they always ask something that you have never thunk before. Because you tell something that does not appear in the newspapers. Oh, I hope do not bore with so much explanation and keep chatting!