Grass doesn't grow...

What does the phrase "grass doesn't grow on a busy street" mean?

I would think it has the same meaning as "A rolling stone gathers no moss", a discussion of which can be accessed by clicking on the link below.

Often it's the (joking) retort of a man teased about his baldness, that his mind is so busy/active/heated, that no hair grows on his head.

Grass doesn't grow on a busy street. Grass doesn't grow on a playground. I've heard this (fortunately not too often) in reference to a man with no chest hair.