Well, if someone goes and grabs 10 packages, and they have 15 random things, 14 of those won't be worth selling for $. If I think about the last 10 things I've ordered, and my thinking of my last garage sale. Nothing was really that valuable that there would be an easy sell.
I would expect the fact that most packages are of low value to increase theft, not discourage it. Lower-value packages carry even less chance of repercussions, and incentivize thieves to steal even more packages to make sure their effort is worthwhile.
Just really difficult (time consuming) to convert a pack of dog bones, a cheap bike light and a random tshirt (last 3 things i've ordered) into $. I think most of those items would just get tossed if they aren't of immediate use.
One thing I hadn't thought of though, is that these items might just be accumulating in someone's horde. Filling up some house or rental storage.
