Everyone is really nice to me when I have my kid(s) alone. The guy at the corner store where I get my beer almost always gives a free candy bar, middle-aged women touch my arm and say "good job, dad".
My wife seemingly gets none of this, and if anything maybe some subtle judgement. Is this a universal experience?
It's this - it's also, in my experience a bit of pity or something. Like, "oh look at that dad out with his kids alone, he probably needs help because dad's don't know how to take care of their children". To me this is where the arm touching comes from.