How is it even possible to steal the whole bag without her noticing immediately and struggling against it? It's from one shoulder to underneath the other arm, you can't just magically warp the bag through a person, even if there is magic in the world.
Also, she's been obviously told, over and over again, by multiple people, to not trust strangers so easily. Yet she still goes "oh, are you going to where I want to go? Golly gee, thank you so much kind stranger"? Sure...