All ideas with LiveYASD_DieHungry as a contributor

Make shopkeepers more susceptible to being paralyzed or put to sleep than they currently are, so it is easier to directly but non-lethally steal from them.

Pets treat the entrance space to shops, or shop-owned items in the shop, as cursed, as a measure against using them to easily steal items. The latter is more likely to be effective, since the first method can be defeated without too much difficulty with a magic whistle.