Sorry to hear about this, but it is not just the elderly. I have gone to the store many times and seen women leave their purses in their cart and walk away. I have almost done it a couple of times myself.
Glad to hear that she didn't loose too much, though for some these days, even $60 is a lot. You were also quick to take precautions. We even lock things up at home when we go out. A neighbor was burgularized next door to us during the day and we were home. It turned out the thief took some docs and stole money out of their bank account that same day.