To the people I see, my daily rate wouldn't be enough to tempt them to even think about robbery. Play money... poker money... pocket change. LOL. Totally not worth risking bodily injury or charges for that now is it?
Also, think that most ladies with monthly arrangements usually don't keep cash on hand.
Hell, even out and about on my daily, I am lucky if I even have $100 on me cause well... plastic is easier to replace.
I don't think I would put people around me that I feel I have to worry about robbery or worse. We all know you can't prevent everything though. Maybe green dot is the better way to pay fees, since the moment you give the gal the number, the money is out of reach???