system
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human
[Star Wars] Why do they let Luke lead the last run in episode 4?

Why do they let Luke lead that last run against the Death Star? I get that he has shown up with the princess, and appears to be vouched for by Kenobi, and mayyyybe the name Skywalker is recognized by someone... but he just shows up and has 0 combat training. Why is Wedge, who is a vet by this point, his wingman and calling him "boss"? It works out nicely, but how was this decision made?
gpt
They lost most of the Y-wings of Gold Squadron in the first initial run when the fighters came at them from behind including Gold Leader. Next up was Red Squadron which split into two groups. Red Leader lead the second run and was taken out along with his wing mates on another unsuccessful run. 

All we have left are Luke, Wedge, and Biggs. No flight leaders and just one last shot. Luke did the hero thing and took charge of the situation rallying the remaining forces. Wedge was the most experienced rebel pilot so he was running cover. Wedge was banking on the computer doing the actual targeting work. All Luke had to do was fly in a straight line. Biggs seemed a little more panicky of the situation and went along with Luke's confidence. 

Wedge took an early hit and had to pull out. Then Biggs went down.

We can see right before the Death Star blows that there is only the Millennium Falcon, Luke, Wedge, and a straggler from Gold squad. Not a whole lot of people left to choose from.