The Taliban don't use RPGs to target aircraft,
How many examples do you want going clear back to 1967 in my absolute certain knowledge!
My Unit lost a Chinook to an RPG hit as it was lifting off with a downed Huey Cobra....I shall start the clock there as I know first hand that it happened.
Google "Tammy Duckworth"....that was a Black Hawk in Iraq.
Then google "Lone Survivor" by Marcus Luttrell....that happened in Afghanistan.
RPG's are very effective against Helicopters.
Read up on how modern day RPG's work with advanced fusing capabilities to achieve an Air Burst.
Then perhaps you will understand a bit more about how very effective the modern RPG can be. We just wish we had something as good as the RPG the Oppo's use against us.