The only thing that comes to mind is maybe defense co. has experience building with indestructible materials, and the specs are for lasting 50 years, which when amortized is optimal for an entity like the government that can dump huge amounts of capital ($40B) at once that a private sector CEO can never do.
It is, to some degree, a jobs program. Whoever wins is guaranteed a lot of work for a long time. So contractors really want it.
I don't think Tesla or Rivian are used to working with government contracts. I'm not sure how much someone like Ford does either outside of mild customization. But defense contractors spend all their time working with the government, building to their specifications, handling the requirements and compliance/etc.
They're simply very very well equipped to work on such a contract.
They'd also be very used to making something for decades because that's what the government wants. Does Ford have a vehicle they make that's nearly unchanged for 30 years? I'd assume even the transit vans have changed a lot in that timeframe.
I think itβs mostly that defense contractors are specialized in selling to the government, which entails jumping through regulatory compliance hoops and placating elected officials by distributing the supply chain across as many congressional districts as possible.
