I’ve always thought that requirement was a little odd. My guess is that their thinking is that even a non-pilot can provide help (looking for traffic and airports, helping when you miss a radio call, holding your beer). My wife always sleeps, so those flights might as well be solo. Fortunately for me, for the trip I used for my commercial cross country, she didn’t join me (it was a business trip and she had no desire to spend the weekend at a trade show).A bit unrelated but I’ve got a lot of XC flights that would qualify for the Commercial requirements that I have to go back and redo because I always had a passenger with me so they weren’t “solo” as I wasn’t the sole occupant.
Can anyone explain how having my wife with me (furthest thing from a pilot) is somehow detrimental to the requirement?