[Yosemitest]

"FL180 is a place I can’t venture...I fly 3,000, to12,000 IFR, depending on winds."

That explains your lack of knowledge.
But you would normally talk to Center if you fly at or over 10,000 feet into most small airports, and while flying enroute at or over 10,000 feet.

[SgtBob]

“That explains your lack of knowledge.”

My “ lack of knowledge”?

I’m in contact with various Centers on every flight I take...what do you mean?