I ride a motorcycle and use a backpack everyday myself. I haven't been stopped ever in my life about a backpack. I have been followed and observed while shopping which is fine with me since I am in a store. If I were to be hassled I would state as mentioned above they are welcome to look at my bag on the way in and out but they will not be keeping the bag out of my sight. Often I have very little of value in my bag but the principal of having the bag is to have the bag on my person, not in a cubby hole in the other end of store while the power goes out, terrorist attack, earthquake etc. happens. I know the likely hood is slim to none but again Im not going to start doing a strip search to shop. Stores account for theft which gets passed down to me if I choose to shop there. If they hassle me too much I wont shop there. If theft is such a problem they could learn a thing or two from casino surveillance systems. Now im just starting to ramble.... Here is a thought if you have a conceal carry permit and want to really make a point then ask if they as employees are allowed to hold customers firearms as you have a concealed carry permit, the store allows weapons and it is in your bag. I could only imagine someone trying to sort out the policy on that one.