http://norml.org/laws/penalties/item/tennessee-penalties-2
Not only is it more serious than a ticket monetarily, but there is a real chance of jail time or probation. Also, I have direct knowledge of a friend who was caught smoking a J but had very little on him. He was arrested, transported, and jailed for a few hours. Ultimately it cost his job and more than $2000 in fines and fees. First offense.
As for the rational, why not? Alcohol is a much more dangerous and destructive drug. If it is okay for public consumption, then so too marijuana. If it is my body, so to speak, and I am not harming anyone, why not? At home, on my couch, why is it the governments business? I'm a disabled vet injured in the line of duty. I have constant pain that causes sleepless nights and loss of locomotion. I use motrin or tylenol to help with pain, but from direct experience MJ helps tolerate it much better and adds to quality of life. I don't use anymore, but if it was an option for my doctor to offer, I would. Because it works. He did prescribe marinol, which is a synthetic alternative. It sucked, didn't really work unless I doubled up, but at $400 per month, uh no thanks.