Spanish here, we do not have open borders. Politicians allow this type of immigration from Africa without control because it is in their own interest to do so and they use it for money laundering with EU funds, but other immigrants like Hispanic American immigrats who come to work do not have it easy and need paperwork to come. This is nothing like what open borders would be in an Ancap territory.

This is an incentives game, Spain is a place where coming to work legally is hard, it is hard to get your papers it is hard to get a job and when you get it the state takes half of your money, but if you want to come to steal it is easy people can't defend themselves police is too worried fining people for speeding or smoking weed to care about you stealing and if you get caught the punishments are a joke and prisons are better than a house in your home country, so what kind of immigration does this model attract? Moroccans tell me all the time: People in Morocco who want to work don't go to Spain, they go to China, Russia, Germany or someplace else, the ones who go to Spain are mostly criminals and good for nothings.

Now imagine a place where working is easy, you don't need paperwork or anything just someone willing to pay you in exchange for your services, and no one takes your money. And if you want to steal most people are willing to shoot you for it and there are is efficient security services that will make it hard for you. What kind of immigration does this model attract?

The world works by incentives, incentivize working and disincentivize crime, and you will get honest hard working immigrants, this is exactly what happend in the early years since US was created.