Credit card required to check in

I was checking in at a casino's hotel and as always they asked for my credit card so they can place a $100 "hold."

Fine, been doing that for years.

Curious, I asked "But what if I don't have a credit or debit card?"

"Then you can't check in."

Whoa...not even with cash?

Whatever happened to US currency being acceptable for all debts, public and private?