Carol, you've done a great job explaining what's in plain sight for most of us to see but you're dealing here with a couple that can't stand far enough away to see the whole picture. They've got their noses so close to one point in the middle of the painting that they'll never see the wider scope of the object as a complete piece never mind the frame in which it's held nor the wall behind that from which it hangs or the light that shines on it.

You've ridden the horse to death & now it's time to get off the horse because they're gonna keep beating the dead carc-ass in the hopes that it'll get up & prove you wrong. It's not gonna get up, they're not gonna get it & "you're right!!! & they're wrong"

Barry