It's in the article. Not just senior = higher pay. Senior = more likely to stick to existing (known good) safety/QC processes. Boeing didn't want QC at all -

It's in the article. Not just senior = higher pay. Senior = more likely to stick to existing (known good) safety/QC processes. Boeing didn't want QC at all - they wanted the guys assembling the planes to do their own QC (which is likely illegal per FAA regulations). Toss in a side of union busting. And a dessert serving of outsourcing to the lowest bidder, regardless of that bidders history in the space.