This is not a corporate policy. But it doesn't matter. If the signs are there, that is the end of the story. One Bill Halberstadt makes an effort to keep up to date with Walmarts and the overnight parking. He has lists posted at both a Yahoo group and at the Discovery Owners website. I use his information a lot.
Many of these local ordinances were the work of nearby campground owners that thought they were loosing business to Walmart. I got news for them. If you have a self-contained rig, you don't need to buy a FHU site to sleep for 8 hours.
The way I see it is if they don't want me to sleep there, they don't want me there at all and we and our money will go where we are wanted. There are other places and the rig has has wheels.
Matt