Then you should know a few laws and ordinances that aren't enforced. My city does engage in "selective prosecution" when it comes to two specific laws: open container and bicycle helmets. The cops won't ticket children or even teens for having "open" bottles, cans, even cups of soft drinks, but will do so in the park if an adult has a beer AND is loud or obviously drunk. Police won't ticket kids under 14 without helmets when they're riding bikes on the sidewalk, but if they're caught on the road, the parents will receive one.
The only open container laws I am familiar with refer to alcohol in the law so I can not speak to that. But the main difference in the examples you are giving is LE choosing to see it happen. With large businesses selling adult products, with signs out front it is impossible for LE or the proper government to deny that they knew the business was there (business lic.) and what they were selling. I do not agree with not ticketing kids without helmets but there again I have never said LEOs were perfect. Quite the opposite in fact.