Because 15 spots back from other cars at Walmart means very little, since 30 minutes later that gap could fill up fast. That place is a zoo trying to find spots is annoying, especially when trucks intentionally take up 2 spots. Why not just park within the stall as best you can? I've found that cars that are intentionally taking up 2 stalls are more likely to get dinged. Anecdotal for sure, but I know I'd be more inclined to accidentally bump someone who does that.