I'm not thin-skinned at all, but we certainly seem to have gotten off on the wrong foot. Let's just let it go. I'll admit to hitting too hard...and I think you should admit to overreacting. Just a thought, your call. Have a good day anyway.
As for the policy of requiring tips being in cash - that's just stupid. You will PO your customers needlessly and reduce the tips for the waitresses. Because PO'ed customers do not leave good tips.
Credit card receipts will make some of your receipts and tips traceable, and therefore, reportable, but so what? Don't you report your income and tips now?