No. this card cannot pull a pilot out from under a vehicle, because in that moment the pilot card is considered an enhancement instead of a unit.

Question: Can this card target a scum unit that is in the discard pile?

The only argument against this would be if the the rules would say that the discard pile cannot be targeted.

We searched the core rulebook for the explanations of keywords like 'targeting', 'discard', 'play area' however, but could not find any rules against this!

Rulings

http://www.cardgamed...geting-a-pilot/

Why would you want to do this?  What would be the benefit?

The most obvious use is returning Snoova to hand so you can replay him and capture an enemy out-of-faction unit. In a similar vein, the event can bring an on-foot Niles or the Boba Fett from A Hunter's Flight back to hand so you can play them as pilots, allowing you to capture or steal an enemy unit. Alternately, you might bring Salacious B. Crumb, Palace Security or Maliki to hand so you can trigger their reactions, which remove focus tokens, heal damage, and find creatures.

Guri is also fun to call back. Her reaction lets you strike first if you lose an edge battle by 2 or more, so she can make edge battles a headache for your opponent if you have units with strong black icons.

More generally, returning a unit to hand can save that unit from being killed. For example, a Better Offer might let you risk putting a high-cost unit, such as Xizor, in front of Yoda or another attacker that will kill the unit. If you lose edge, the unit will retreat hand, allowing you to replay him later (and possibly use him against an opponent who now has a much weaker edge hand).

If you're trying to close a game, you might strike with Xizor in one engagement to focus defenders, then call him back to hand so you have three pips instead of one for the next edge battle.

A Better Offer can also be used to clear damage or focus tokens from units, such as Bubo, who protects Scum characters. Alternately, you could call a Black Sun Headhunter to hand after striking with it, discard it in an edge battle, and play Show of Force to bring into play ahead of your final attack.

This will rarely come up, but because A Better Offer returns cards to their owners' hands, it can also take away enemy units that the Light Side player has control of through Redeem the Fallen or Search Your Feelings.

You can also use this on any enemy unit with Death Mark on it to bounce it to its owner's hand, and that has all the usual benefits of removing an enemy unit at action speed.

Wow!  Pretty powerful card!  Thanks to both of you for your insight!