Well they do produce virgin olive oil and the land is very expensive especially if it has productive olives or other crops. As I understand it Spain is better known for eating olives rather than quality oil.
Are you registered with the EU? Your olive orchard most certainly will be and I would be very surprised if someone is not claiming a subsidy for your land (does any local farmer do you a favour such as cutting weeds or do you pay someone?). Checking it out should be easy as it should be available on the internet for all to see also you can see what your neighbours are receiving in subsidies, that might come as a shock. By law all farmland has to be registered with the EU and all businesses working the land such as yourself, otherwise you would probably be liable for fines for collecting things from the wild and selling them which is a relatively recent law going through or passed, I only heard about that one a year ago!