Mostly they're named or ranked characters. One officer with a group of guards, one spellcaster in the patrol, one strong/unique monster guarding something... Suddenly having 4 of each in one place wouldn't make sense.
Of course not, but you can build a unit with character and make it standard- instead of having a mob of them have just one standard- if you have 4 players, sure it's worth 1/4 the normal XP, but in the rest of the crowd it's a tougher but similar enemy (especially since you can build it knowing what you want). Just because you have 1 of an enemy doesn't mean it has to be special, and repeated fights with Specials, or fights with multiple specials can become downright mind numbing, or can load on the XP (you're already giving them a fight roughly as difficult as just 1 standard character, but xPlayers the XP).
Basically, the 1-per-player part of Standard Characters isn't mandatory, if you have 4 players, you can have 1, 3, 10, 17- at the end you just add'em up, divide that number by the number of players, and multiply the XP by that amount. I think that'd be the best solution- make the officers higher XP costing Standard NPCs instead of Specials- add Tough, Veteran, or Cagey to them to prolong the fight or make them more difficult.