In that case you don't own your prescription medication. Reselling alcohol is another legal gray area, but absolutely prohibited to sell to minors, so not being able to dispose of your property how you see fit I guess you don't own your alcohol either.
You are completely correct. Same with some other common products too. You can "own" all the uranium you want, but as soon as you make one little nuke the government gets all up in your face. It's annoying.
You're trying to argue against general rule by pointing out things that have been explicitly, purposefully excluded from that general rule. That doesn't make any sense. Alcohol and prescription drugs have explicit sale/resale restrictions in the law.