Question

Why do people assume that I am more than I really am?

In class,
My peers think I'm brilliant.
I'm not really.
I just know how to apply the stuff.
That and I've had this stuff before.

At work,
Whenever I'm on the sales floor,
without my vest that says "cashier,
Customers assume that I'm a manager,
And that I can solve all their problems.
Fortunately,
I'm decent at solving problems and learn quickly,
So I can get them the answers when I don't know them myself.

I just talked to some grad student,
Asking him about his computer.
He kept calling me sir.
WHY?!?!
I know I look younger than I am,
I hear that all the time.
This guy is obviously older than I am.
Why is he calling me sir?
(Of course, I guess it's better than be called maam...)

People seem to assume that I am more than I really am.
Why is this?