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I don't think you're reading it correctly. Improbable Age is the in-universe example, and Underage Casting is the acting example. IA is when Doogie from Doogie Howser, M.D. is too young to be a doctor, while UC is when Neil Patrick Harris is too young to play the character of Dr Horrible on Dr. Horrible's Sing-Along Blog. That's why UC is trivia.
From what I understand, Underage Casting is supposed to be about characters being far too young to hold certain professions (like a 22 year old being a world class neurosurgeon for example). Instead, more than half the examples seem to be people pointing out that the actors aren't the same age as the roles they play, in some cases pointing out a one or two year difference.
Am I reading the example wrong? If not, deleting all those examples would leave a very bare page, it seems wrong for one person to unilaterally cut that much out.