True, and they know that. They also accept the idea that they suck enough on there own that they couldn't earn them anyway. If they shot down one guy in the horde mission they earn .25 perks. If they shoot down one guys defending against a horde they earn 2 perks. You think some may try defending some times?
Some would.
But in my opinion the overwhelming majority would not. Perk motivation only goes so far, and that is not a long distance. We could notice that with the unwillingness of balancing sides despite having an enormous perk gain advantage, and the very high usage of low eny birds, which hardly earn you perks at all.
One motivation for preferring the attack missing so far in this thread (or maybe it's just me who missed it, please ignore me in this case):
Players love to have the initiative. As attacker you can choose when and where you strike, you can abort the mission when it doesn't run well with less impact on combat morale than a defender can. Most players get quickly tired after a number of base defenses, constantly reacting to enemy activity is apparently very frustrating for many. (I might point out that the most renowned defenders are for the most part players of significantly above average skill level) Even when the defense is successful, you will start to read a lot of "I'm tired of defending... let's grab a base!".
After all these years of heavy gaming, I have yet to read the opposite expression on any country channel.
Players love to attack for the sake of attacking. They endure much more losses as long as they still have the impression it's them who dictates the action.
And this not entirely a bad thing, as this game lives from the attack. It depends on players running into enemy defenses again and again. Attack creates combat.
There have been quite a few proposals for getting more players to defend. Some are not bad in my opinion, some won't work well.... but in the end, it's preferable that the gameplay is not totally balanced between attack and defense, and it's very important that the defense doesn't get stronger or just more attractive than the offense. This would stall the game quickly - we could see the effect when the new towns had to be 100% down with no flag being there at all.
Once a huge number of players have the impression that "it's useless to attack at all", AH will run into trouble, unless there is a total and radical change in MA gameplay mechanisms.
Now we can bewail that many players give up far too easily, are demotivated to quickly and so on... but that doesn't matter. In the end it is what it is, and AH has to accept the players for what they are.