Target vs. Walmart

How many bad experiences do I have to have before I stop shopping at Walmart completely? Once again I was at Walmart getting my groceries for a little cheaper than anywhere else within a 5 mile radius (that I know of). I was doing so well with timing before Baylin's nap and then it happened. At check out the cashier made an error and told me she could not fix it at her register and I would have to go to the service desk. I looked over to the GIGANTIC line at the service desk and knew that I had to join them. So Baylin's nap would be delayed and he would have to sit in the shopping cart tired. 30 minutes later I got to the front of the line to find out that we needed a manager for the error the cashier made. That took 2 more minutes for them to come over and tell me that they would have to talk to someone else; another 5 minutes. Than they told me to follow this other woman to a register where she would have to return every item I had by hand keying in the numbers and rekeying them in again for repurchase, 10 more minutes. While I am waiting she did tell me that the cashier could have done it at her register and it would not have taken near as long ( by this point 47 minutes ). Baylin is getting really fussy at this point and I am really thinking that this is just not worth it. I asked if they ever compensate for experiences like mine and she said yes. She grabbed a gift card and as she was adding a credit to it I was thinking $20 would make me feel better. She gave me $10. So I walked away (now 50 minutes later) frustrated, unsatisfied, and regretting walking in to Walmart.
Now, if I was to compare this experience with several other similiar experience with the company to my experiences with Target. My kids behave excellent every time I go to Target. I have never had huge errors there. I have never waited in a long line at Customer Service. In the end if I would drive a little further and pay just a little more I can have a better experience ever time. So why again do I go back to Walmart?