Lol, urine is sterile when it comes out of you, but it quickly becomes FULL of bacteria. Just try peeing in a bottle and storing it at room temp for a day, then take a whiff.
I also wonder about your claim that partially-composted poo is less smelly than fresh. Many things become MORE smelly when they are partway through the composting process. Not only urine. Leave a tub of preservative-free bean dip out for a few days, then smell it.
You seem to have less real word experience than the average RVer. Are you perhaps very young? Or have you lead a mainly indoor life?