Proof of Sufficient Financial Means

I was not asked for anything like this when I entered Spain as a tourist.

Okay, I will bite. I have flown enough times to Europe via American, including Spain, and have never seen such a demand. Can you please cite where it appears on aa.com?

Do you have a round-trip ticket? If not, how long are you planning on staying, and how are you exiting?

That might not be relevant, but if there is any reason to suspect you plan to stay for a long time, they might want to verify that you have the financial means. The airline is responsible for returning you home if the country you are arriving to doesn't admit you.

While technically you could be asked for it, chances are almost zero you would be asked. If Immigration thought you were trying to enter for work or for longer than you say, it might arouse their suspicion. In all my decades of travel to Spain I’ve never been asked. As long as you have your return ticket and can show it you should be fine.

Every border agent for every country has the right to ask you to prove that you have the financial means to support yourself for the time of the stay in their country. They don't typically ask unless there is some indication that you aren't a true tourist. One should be prepared to show some evidence of an itinerary, a hotel reservation, cash and or credit cards. And as mentioned above, a return ticket.

One time I was asked to show proof of funds. I was in my 20s and I was backpacking; this was the 1980s. I guess I looked like a poor student. I was asked by the immigration officer to show a return ticket. I did not have one because I was planning to travel on a special fare that could only be purchased 3 days before departure. The officer then asked me to prove I had funds to buy the ticket. I showed the immigration officer my credit card and that was sufficient.

It is extremely unlikely that you would be asked to show proof of funds as a tourist. You don’t need to carry your bank statement.

It is a real requirement, but rarely would ever be asked. Lets be honest with ourselves, if you are white, carrying an American passport, above a certain age, a return tickets in a few weeks, they will never ask. Be a POC, young, no definite plans, maybe from a South American or African country, then you can be sure to be grilled. It is a firm requirement if you are from a country that is required to obtain a Visa to visit Spain. (or if one applies for an extended stay Visa)

Interestingly, they did start to question some Brits coming down for their extended holidays about a year ago, even stating that an amount of 113.40 euro/Day was required. After reporting and some discourse, the Spanish government called reports a hoax, so who knows.

Other common items that can be required is, proof of onward travel and proof of medical insurance coverage. You may also be asked about your plans and where you are staying and if you are coming to seek or accept work.

this was also on my Icelandic Air website about documents to bring to enter Spain
Recently on other FB websites I have seen this same question asked. It sounds like you could bring a copy of your banking info with balances. We go to europe twice a year and have never been asked. I have not been to Spain in 30 years. Hope this helps.