The original question of this thread was about why there are lightly perked vehicles, but no lightly perked aircraft. Why is that? It seems to work for vehicles, so what's the rational behind it, and why isn't it used for aircraft?
Lusche took at stab at an answer here, but the thread mostly evolved into pros and cons of light perking some late-War fighters.
In my subjective opinion, the performance differences between individual tanks (notably armor & penetration) have a somewhat bigger impact on the results then those between the planes.
And actually I think Vinkman just said the same thing from the opposite point of view, when he stated:
Most planes are not way better than other planes.
It might also be the case that perking aircraft came first; just a few aircraft were perked--but at medium and high costs. When vehicles came along, HTC experimented successfully with light perking of some of the units. But perhaps they felt it wouldn't be right to go back now and lightly perk some fighters...dunno.
I think someone else mentioned along the way that tanks are also more vulnerable (being hunted by both GVs and aircraft) so they wouldn't support as high a perk cost as aircraft? Although, the Tiger II seems roughly in the same neighborhood of cost as the Me262...