How come no one flies Arvel?

Isn't he from the Transport Exp? If so, that explains why.

No, Arvel is from the first A-wing expansion. I personally would rather take Gemmer for a point less. He gets more defense if you can get close, which is where you want to be with an A-wing. Throw stealth device on him and PTL and, with focus+evade, he's a five green dice evading machine at range one.

Arvel is just not a proper A-wing. For his cost, his powers don't fit right. He's too high a PS to be a good blocker, which is what you want him to do with that ability. At a 6 PS, it's odd he doesn't come with an EPT so you need to use Test Pilot to give him one instead of rolling with two. His power just doesn't get used all that often to make it worth it. It's better to take a green at 4 points less at that point, or as the above poster said, Gemmer with his super useful ability.

So Gemmer or Green?

I prefer Gemmer to Green but it also depends on your points. I also think that Gemmer with predator is extra lethal but if you don't have the points, a Green with PtL is still pretty darn strong.

How come no one flies Arvel?

he's like Tycho (imo) in that they're both too expensive for what they do

that was a theme across all A-wing pilots until Rebel Aces and Refit hit, thanks to FFG overestimating the impact of ordinance in Wave 1 (not really to blame them, they'd have to be psychic to see years into the future ) but I don't think Refit makes them worth it either.

In Arvel's case, his ability is pretty situational when you can get Jakes for one more or Gemmer for one less.