Some caregivers have a blanket permission form that allows them to take the kids anywhere within a certain radius of the house. That means a quick trip to the grocery store, etc. is usually ok. It also allows for fun impromtu things like the kids got fascinated by a storybook about guinea pigs and the caregiver decides to take them to the pet store to see some for real.

Personally I look at home daycare as my job meaning the moms can't leave work to do their grocery shopping even if they take their blackberries with them so we shouldn't either. We have evenings and weekends too just like them. On a day you promised to bake with the kids and discover you have no brown sugar and think it is worth a trip to the store to get some and maybe let the kids pick a new box of crackers for snacktime while you are there is different than doing the weekly shopping and dragging the kids along. Personally I would rather stay home and get some housework done and do the shopping on my own later if I really had to do something other than straight daycare during the daycare day.