I'm gonna need a source for "it's never appropriate to u-turn immediately after exiting a junction."

My feeling is that, usually people who keep omitting proofs for being trivial either don't have a proof, are too lazy to write one, or just want to mess with people. Imo just bad form; what is obvious to the writer is not necessarily obvious to the reader.

The "proof by intimidation" wording was inspired by a reddit post; not trying to imply there's some intimidation happening here https://www.reddit.com/r/mathmemes/comments/uictdw/common_proof_techniques_shared_by_one_of_my/