I'm not sure if this applies to smaller parts like this, but traditional aerospace suppliers are allergic to iteration. Everything must work the first time. You can see this in how many rockets SpaceX has blown up vs. how many ULA has blown up.

I imagine it's similar to what we see in software, where we see mega-waterfall projects delivered for the government cost way too much and still fail, and where tech companies & literal hobbyists can deliver higher quality software more quickly by avoiding an overbearing planning process.