Maybe I'm wrong, but the "mercs" that you quote, play in whole another category than V.
Morgan Blackhand, Smasher or Weyland, like V in the Path Of Glory, can choose for who they want to work, what they want to do and how to achieve it (in short, they can be picky and avoid fixers).
But V during the whole game (before the path of glory, at least), V is no one. V is a simple little merc among others. So he only have acces and can accept jobs that fixer offers. I really don't see V ring to Arasaka or Militech doors and say : Hey guys, you don't know me, but still, do you have jobs for me ?
A bit like a begginer actor, totally unknow who would want to directly work for the biggest studios.
If V was like Geralt, a well known/famous person, why not... But it's not the case