F4U-1C as stated was perked because at one time it was insanely over-used and was unbalancing the arenas (WELL before my time). Also, only 200 were built.
Ta-152 is perked because it was extremely rare.
Me-163s and Me-262s are perked because they are ghey. They're ghey even WITH the perk.
F4U-4 is perked because she's the best prop fighter in the game, and guaranteed if she wasn't it'd sure shut up the "Perk the ElGay!" whines.
Tiger is perked because it's the best tank in the game.
La-7 is not perked because she's quite frankly NOT the game-breaker people make her out to be. Personally, I love shooting a guy down, watching him up an La-7 while I'm egressing thinking he'll run me down and take revenge, then I shoot him down again.

However whenever HTC implements the perked ord option, the third cannon should be perked for the same reason as the Ta-152/F4U-1C. There just weren't that many built.