There is a "Daily Urine Splash Estimation in the US" section in their paper (I can't believe I looked this up). There equation basically makes these assumptions:

1. 56 million non-residential urinals in the US.

2. average of .22 L per "void" (a void is one pee session)

3. I think how they estimated average usage per urinal was weird and frankly wrong - they estimated each person would have between 3 and 6 "voids" per day, and each urinal would be used by between 1 and 2 people per day. Anyway, in any case that leads to an estimate of each urinal being used between 3 and 12 times per day. I think this estimate is way, way too high, because at the low end 3 X 56 million = 168 million, so on the low end they are estimating that, on average, every male in the US makes at least one public urinal pee (and, on the high end, 4 public urinal pees!)

4. Based on their data they calculate a value of ~1% (0.965%) of pee gets splashed onto the floor.

So you multiply that all together: 56 million * .22 * (3 on the low end, 12 on the high end) * .965% = about 350,000L on the low end, or 1,400,000L on the high end, so they said "on the order of a million liters".

Again, I can't believe I spent time looking this up and writing this comment.

I think you mean 165, not 16.5?

But probably, what, only 50m use public restrooms, but some use multiple times, so 150 uses / liter seems reasonable.

That's under 10ml of spray / spill per use, which is maybe a little high but not too crazy? I've seen some pretty bad spill results at work...

If you consider bar restrooms, that is probably skewing the average higher…

I think you drastically underestimate how much 10 ml are.

That's not achievable with backsplatter, that's called "missing".

It's almost but not quite exactly two teaspoons, which is certainly a plausibly achievable amount, but as you say, likely not by splatter.