Public/Private property vs. the Constitution

I may be delusional or under the influence of
some illegal substance by actually thinking
this may passed as a future law, but here goes it....

Everywhere we go in our daily routine we are reminded
how constitutional rights do not apply in a privately owned
building such as your employer, the gas station you stop
at, the school you attend, the large retail superstore
that destroys the american economy.

You have no rights to carry a weapon, speak your mind,
question the motives of your "superiors" while in this
privately owned buisness or school.

Here is why i am delusional....

If these buisnesses/schools/public parks are
in any way funded by public tax payer money
or authorized to collect tax funds for the local/state/fed
government, what is their justification for claiming
they are private property and denying constitutional rights ?

Here are some examples to support my delusion.

A college, even if labeled a traditional private college,
still accepts tax payer proceeds in the form of scholarships
or grants for their science/research depts.
But they claim they are private property ?

A gas station collects state sales tax on products
and federal gas tax applied to fuel
But they claim they are private property ?

A super retail chain or manufacturing company,
well this could include any corporation in the US,
receives tax cuts to be invited to set up buisness
in a specific city or town and also collects state
sales tax on products sold.
But they claim they are private property ?

To actually claim the title of private property
a buisness should have no ties to the state/fed
government.
Only then could they have the legal right
to deny the Constitutional rights of Americans.