I don't have much issue going into stores right now. I get in and get out to limit indoor air exposure and everyone has masks on to keep particles from someone coughing getting in my body.If you feel safe in a Walmart right now, I think you may be in the minority there. I honestly don’t know anyone who feels safe in any populous, public, indoor space. And to be fair, the science says we really shouldn’t feel safe in a circumstance like that right now.
Most people are going to stores right now because they need food and whatnot—not because they want to enjoy a day out at the local Walmart.
And, much like tracing moderate spread back to parks would be next to impossible given our current testing and contact tracing infrastructure, tracing an outbreak back to a Walmart is much the same. There are too many people present and the spread isn’t likely to be severe enough for the cluster to be obvious.
However, I have serious concerns with going to bars, movie theaters, offices, and most anywhere that includes long term indoor exposure unless they can show they are constantly cleaning the air with UV to kill the virus (the airlines are about the only ones I've seen do this).
Parks I don't have issue with for anything outdoor, even when it's busy. However, I won't do indoor queues or theaters that create a prolonged exposure - a gift shop is fine for a few minutes though.