It is inadvisable to go shopping for quilt fabric at a local convenience store.
As great as 7/11 is, you are never going to find fabric for your quilt there. It ain't gonna happen. The same is true in other things too. My cat is never going to bark. He might bite the mailman, but he is never going to bark. I can't bake a cake in my car. I've heard of cooking things on your engine, but I can't imagine it would taste very good.
I forget this sometimes. (I don't sound very clever do I.) I go along, enjoying my life, loving my friends and family and thinking that they can supply all of my needs. My 12 year old son shouldn't be the one I run to with concerns about my husbands job. My husband isn't the one I should talk to about feminine hygene products. The mechanic isn't the one to discuss the relative virtues of breast feeding with. For the record I haven't done any of those things...well I've never talked to a mechanic. I look for fabric in the wrong place.
As shopping goes, it doesn't really matter that you look in the wrong shop for the object of your desire. It extends your trip, makes the outing last longer, and puts off the inevitability of going home to a sink full of dirty dishes, and stacks of laundry. Those arn't necessarily bad things. However, I suspect if you go to 7/11 for quilting fabric, you're not really looking for fabric. My guess - you're thirsty and have a disconnect in your brain. (7/11 is a most excellent place to get a big, cold, drink.)
It is a problem if you start bludgeoning the shop clerks for their lack of product. Think about it.