Urine is sterile. Toilets are not. I'd say it's much more hygienic to urinate standing. We don't sit down because we don't have to. It's really as simple as that.
I can buy the argument for "I prefer not to sit", but I'm not convinced about the hygienic aspects.
[1]: https://www.popsci.com/urine-sterile-drinking-pee/ [2]: https://time.com/4908654/cell-phone-bacteria/
Men urinate standing up because they can. That's it. End of story.
Heard from the heavens: First In The Bag, Pee Standing Up
Adam immediately gets excited. "Oh, that would be so useful as I'm in the fields toiling all day. I wish for that ability to be bestowed upon myself". And so it was, that Adam could now pee standing up.
Heard from the heavens: Second In The Bag, Multiple Orgams
I love HN.