I might be too used to D&D, but I don't mind if the "wizard" of the situation is more powerful and versatile of my sword and board crusader. He is using magic, I'm waving a stick. If we had the same level of power or usefulness it'd make me feel like magic was not powerful enough
Very few people react the way you've described; most would be unhappy that they didn't get to play alongside the wizard in a meaningful fashion. It's important to note that, in d20, the vanilla fighter as written is
completely redundant, not merely weak, and it's only incompetence or massive house-ruling (including self-nerfing) that pulls him into playability vis-a-vis the wizard. Ars Magica is a much cleaner, much more honest example of this phenomenon.
In my experience, and this is just based off where I live, parties don't do that. Everyone's had at least a half dozen asshats they know of in their gaming experience who are in it for pvp, and as a result no one I know compares PC's.
Ugh. Been there. I hate heaping duties on the GM, but this is something that he could stop if he wanted to. The main problem with this sort of thing isn't that it happens, but that it happens a) in the wrong system and b) in the wrong games.
d20 is a Bad Place for this because its intraparty balance is so utterly crazytown. Suggestion alone pretty much can end PvP conflicts, and immunities to various shticks aren't to hard to come by. Winning a fight with another PC is ultimately pretty random, depending on the books allowed.
The wrong place is far more important, though. The fact of the matter is, stock fantasy adventuring is a terrible, terrible place for hard-core paranoid intraparty conflict. You wouldn't even bother adventuring with people that were this dangerous to yourself (hence the sheer unplayability of kender). You're forced into a railroad before you enter the game, having answered "Do you want an adventure?" with "N" from jump. Now everything that follows is contrived and stupid.
This would be way more useful in games like VtM, but, weirdly enough, I've (almost) never had this level of conflict in a oWoD game or any other political skullduggery game. The intraparty conflict types seem to gravitate to the very kind of game they shouldn't be playing to scratch that itch.
Meanwhile, I sit down to run a game about psychotic rape cannibals with chronic backstabbing disorder, and everyone holds hands and sings kumbayah.
"Let's send an emmisary to the Lupines and form a mutual protection pact!"
"Games over, everyone take your sourcebooks and burn them. Seriously. Burn your motherfucking books."