There are sparrows and there are sparrows. I suspect that the staring-at-humans is learned behavior. That, or they're seeing a reflection in the lens. A totally non-skittish white throated sparrow.
This house sparrow cracked me up. He came and sat on the fence within touching distance. Definitely learned behavior. Have food? I'll wait for a hand out. Sometimes I wish I could do human portrait studies as easily as I can grab bird studies.
Totally unexpected, the fox sparrow appeared. Someone had tossed down bird seed. The fox sparrow eats like a parakeet. "Beaks" the seed shell until the shell drops off, then has the nut to dine on.
Again, maybe the fox sparrow saw reflection in the lens. It didn't move off or show fear. This was not ordinary sparrow behavior and a great oppportunity to watch the eating process.