I like the way that the IL laws put it- it seems clearer. I hate the "is it a public place" argument. Unless there are certain people that they don't allow into their store- like nursing babies- then I consider it public
Section 10. Breastfeeding Location. A mother may breastfeed her baby in any location, public or private, where the mother is otherwise authorized to be, irrespective of whether the nipple of the mother's breast is uncovered during or incidental to the breastfeeding; however, a mother considering whether to breastfeed her baby in a place of worship shall comport her behavior with the norms appropriatein that place of worship.
http://www.lalecheleague.org/Law/summary.html