Roger wrote: "...in my opinion is the potential health hazard created by possible contamination on your hands when you don't use TP..."
Well, if you are a healthy person, you cannot catch something from yourself or excrement. Urine is sterile. Poop has your own bodies bacteria which you accomodate, anyway. Getting clean is a matter of avoiding crotch rot more than anything. As far as ingesting a few bacteria, it isn't a problem. Anyway, intimate partners are generally immune to each-other, too. Unless you have a tape worm, ring worm, or other pathogen/disease, this is mostly a social issue. But, I did say "healthy person."
Here in the NE of the USA, TP is not a problem. Generally, we get rain or heavy dew most days. In the Siera's, I would not burry toilet paper, but pack it out. This is very much determined by the environment you hike in. You really cannot just categorize it independently.