In my city, olive trees thrive like mad. I could probably start a business selling a few tons of brined and jarred olives a year entirely on free produce.
Lemons, too. I could go for a 15 minute walk in any random neighbourhood and come back with 10 pounds of lemons.
I live in Canberra, Australia and we also have an excellent climate for olives and lemons. Apples and practically all citrus also do well and plums and other stone fruit grow like topsi. Figs too.
Deep inland, 600m elevation
We need to protect many of our fruit trees from birds, but not olives, apples, or citrus
Careful. I wouldn't be surprised if people get weird about the origin of said fruit. We both know that those olives in the grocery store come from trees like the one you're talking about. But "I plucked these from wild trees in the park" might not go over all that well.