Cows say...beep beep?

In my developmental psychology class today, my professor was explaining that children who live in a large city, (she used Chicago, Los Angeles, and New York City as examples) wouldn't know what sound a cow makes when they're at a young age.

What?

Think about it, when you're teaching your kids about animals and noises, the first thing that comes to mind is farm animals, then maybe cats and puppies. At least that's what my class said, but we live in rural Pennsylvania.

Apparently in highly urbanized areas, cows aren't that common. (Duh.) But it actually surprised me that when teaching young children their animal sounds, parents don't automatically start with farm animals. So what do they start with? Dogs, cats, and...pidgeons?

I guess it just baffles me, when in PA all you have to do is drive two miles in any direction and you'll find a field full of something, cows, sheep, llamas.

Any thoughts?