I grew up in a rural area, and sometimes find 'city logic' amusing.
Need to urinate? Pull over, get out, and water the grass. This is older than time, and a non-issue. Really. It isn't an issue to me.
Defecation is obviously in another category.
Peeing in a bottle is also a non-issue. As far as I am concerned, if a woman can breast-feed in public, why can people not urinate into a container inside a car?
(Both are body parts with sexual, and non-sexual purposes)
And women can do so too, with the aid of such things as this;
https://www.amazon.com/Standing-Resistant-Urination-Portable...
To take a step back, are astronauts the next "put out" class? Tank drivers on patrol? Park rangers? Long haul truckers? Virtually all outdoor, in the country type jobs?
And more oddly, at first all I heard about was urination in bottles. Then massive outrage did not appear. Now defecation seems to be added?
Note: Amazon sucks donkey balls, but let's address the true suckage, not what I see as a non-issue.