I don't understand this. I can pay for take out with gold bars or diamonds if I want. Money is legal tender and must be accepted if offered to cancel a debt but it is not the only thing that can be used to pay off a debt.

True but for tax purposes purchases from a commercial entity like a restaurant probably require legal tender of some sort to prevent the creation of a gray market.

It's against the law in both New Jersey and Nevada and has been for a long time. The gaming commissions in both of these jurisdictions can regulate pretty much any commercial transaction there is in the casinos, including player-to-player matters. It's just that most of the time a lot of these smaller things aren't enforced or are unenforcable as a practical matter.

The initial issue was that there were Federal guidelines about what can and can't be used as currency which is a little different than bartering here, and the state governments had to enforce it somewhat. I think there were tax and accounting issues with the casinos IIRC, we had an article in our trade press about it a while back.

Also, the CCC fines for a lot of things.

It's also pretty universally ignored in Vegas. I've NEVER seen a waitroid hand back chips to a player attempting to pay for dinner at the poker table (though I think I have seen 'em refuse chips in a restaurant).

In other jurisdictions I have seen waitroids going through a routine with players attempting to pay for something with chips... They simply make change for the chips and hand the full amount of cash back to the player, who then hands it back to the waitroid (usually after some strange looks and back and forth discussion as to why this odd procedure it taking place). That way, they aren't paying for the item with chips, they're just cashing in their chips, and then paying for the item with cash. Demonstrates the absolute stupidity of the regulation.