While cash can be stolen, you can be sure that only the amount of cash you are carrying can be stolen, and once it's stolen, you know exactly what you've lost and that's the end of the matter. With credit and debit, it's much more ambiguous how much you are liable for, both in terms of money and time. And it's certain that the time cost will be greater.

Also, so far I have never had any cash stolen, but have cycled through several credit cards due to fraud.

(I don't mean to say that credit card transactions are unsafe. I just want to provide a little balance.)