Just to bring some folks up to speed, and not specifically directed at you: There are places in the country where people get around a lot by bike, bus, on foot, etc. Even when we drive somewhere, parking can be some distance from our destination. And we have all of our stuff, such as layers of clothing, crap for our kids, electronic devices, etc. This is probably typical in most places where there is decent public transit. In my locale, it is not an uncommon sight for regular people to have backpacks. Plus some freaks, but freaks tend to be harmless.
Retailers seem willing to accommodate this. As I've mentioned above, I walk into stores all the time with my backpack. Yesterday, I got dropped off downtown with the kids. While they were busy with their activity, I had some time to kill, and went off on foot to a bank, a coffee shop, etc. Nobody batted an eye at my backpack. There was no infrastructure or personnel at any shop for dealing with my backpack. I have no idea if any store had a "policy."
So, that's the status quo. Those who wish to challenge the status quo, for instance by prohibiting backpacks in stores, are the ones whose task is to show that they have thought about the practical consequences.
All of the "what's so hard about" questions seem to be a debate tactic intended to pass off the burden of proof onto the other person.
