Even when sitting down we have to aim the nozzle manually, so it's just sitting down for a moment then getting up, which normally is more work than standing there for a moment.

And (at least for me), it is more comfortable peeing standing up (albeit that might be because of a lifetime of doing it like that).

Another compromise is to pee in the shower. or better yet, on there indoor plants, this way we don't need to water them.