Yes, from an economic standpoint that's the primary reason. Boeing primarily does spaceflight contracts on a "cost-plus" basis (i.e. their profit is a fixed %, such as 10%, of their their expenses), where they make more money if they take longer and use more expensive components. SpaceX primarily or maybe even entirely does their contracts on a "fixed price" basis, where they make more money by doing things faster and with cheaper components.

In a rationally-run corporation (of which real ones are merely an approximation), these profit incentives will trickle down into things like the culture of the team and the decision-making criteria used and decision processes used.

The cost-plus contract was popularized by the US military in WW2 because it allows a way for the military to sign a contract without the scope of work being known - bypassing most or all of the contract negotiation phase, and saving months or a year. The military can say "just make it happen, I don't care how, just do it, and I'll pay you your costs + 10%". https://quizlet.com/11795259/251-flash-cards/

However, in WW2, the cost-plus defense contractors still worked very fast, despite the lack of a profit incentive for fast work, because they were motivated by a survival incentive (if they didn't work fast enough, they'd lose the war and possibly be killed).