I don't think it's shame; just practicality.<p>If I'm about to hand someone a large sum of cash, it's generally not practical to carry that in my wallet.  Plus, that money likely came from, or is going to, someone who <i>also</i> doesn't want that money mingling with "their" money. (likely someone who will be dealing with several such envelopes)<p>And, in general, you don't want to have more money than you owe in front of you, while you count out a criminal's portion. If you do, you'll quickly find that prices go up.<p>There's also plausible deniability. Stacks of cash attract more attention and aren't as easy to explain away as envelopes.  And envelopes of cash have the hallmark of the legitimate proceeds of a cash-only business 'on its way to the bank'.  If the money is mingled with your own, that's a harder argument to make.