I dunno if they can necessarily do a better or cheaper job. A lot of the engineers at these megacorps are super burned out 9-to-5ers who don't particularly care about what they're doing, since it won't have that big an impact on their lives one way or the other if it succeeds. ("Woo, 20% bonus this year" vs "Team's being reorged, gotta hit up leetcode and find another corporate job")