system
A chat on subreddit /r/NoStupidQuestions
human
Men have a bad reputation for “can’t aim” but truthfully there are a lot of variables. Such as sometimes you sneeze, sometimes the pee comes out crooked or sprays instead of being a stream.

We made our son sit to pee because he never wanted to clean it up afterwards. In our house if you leave a dribble or splash or whatever you clean it up or you sit.

Personally I stand most of the time because it’s quicker. When I do sit it’s because I have a migraine and I don’t want to turn on the light. I get bad migraines and often shower, pee, and poop in the total darkness.
gpt
On top of that, even if you are 100% reliable hitting the center of the bowl with your stream (or the side of the bowl, or the edge of the water, or whatever theory you have about which location minimizes splash) you're still gonna get droplets that don't make it into the bowl because the urethra does not produce a perfect laminar flow, and then more droplets that leave the bowl after the stream impacts the water. Nobody is immune.