For the sake of argument...
The driver or pilot of the rescue vehicle or plane should also get perkies for a successful rescue. Maybe also a small percentage of the downed pilots perks.
Then also, there should be an easy way to check the perks that the downed pilot has accumulated to see if it is worth the effort of rescuing him.
If the downed pilot shot down 7 Me 262's, and if the rescuer got a percentage of the perks, that would encourage people to rescue the guy. If the downed pilot only got an assist on a P-40B there might not be much of an incentive to go help.
Best Regards