There's something that, to me, makes this a "safety trumps etiquette" issue. (I'm not giving Friend a complete pass, unless she complained to the neighbor before this.) My knowledge of the following would have had me knocking on her door the first time I saw a squirrel!
Raccoons can carry both rabies and canine distemper. And they may seem cute and fuzzy - well, they are - but they are also very efficient fighters. If a Labrador comes across a coon, the coon will win the fight, possibly killing the dog; at the least, stitches will be needed. No, I'm not kidding. They can also transmit something known as "coonhound paralysis," for which there is no medication and no cure. And though raccoons are cute and fuzzy, and may recognize Neighbor as the person with the food, they don't love her. If s/he was to try to take it away, they'll protect their food.
And the little fiends will make a mess out of the garbage cans. Like the one who, once we figured out how to keep him from getting the lid off, tipped it over, broke in the bottom, and rolled it up the driveway, leaving a trail of trash! And, if they know where she keeps the food, they can break in and get it. We also had to cover the screen door with hardware cloth, after he broke in 4 times!
Deer can carry ticks, which means Lyme disease, Rocky Mountain spotted fever, and ehrlichiosis. Since ticks drop off once they're full, guess what might be hanging around in Friend's back yard? They can also carry anthrax. Not to mention the traffic hazard, and other dangers.
VorFemme is right to mention bears, too. If Friend is anywhere near bear habitat...
I would be very surprised indeed if there wasn't some kind of ordinance about feeding wildlife.