I’m sorry but what do you mean “rest of the story”? They parked in a area that says no overnight parking. The end. Follow the rules and you don’t get your truck booted. The end.
By the rest of the story I’m talking common courtesy, such as asking them to leave before being booted.
Now Walmart may have tried that then Trucker’s became belligerent causing Walmart to just boot and tow, that could be the rest of the story.