> My point would be that while SpaceX does save lots of money, it doesn't do so by producing cheap or less reliable rockets

Indeed, if we assume that the each launch is an IID binomial coin flip (which isn’t really the right way to evaluate right-censored data), and observe (by reading Wikipedia) that SpaceX has had at least 450 successful Falcon 9 launches since the last in-flight failure, then they have at least five nines of reliability:

0.999995^450 ~= 449/450.

Which appears to be an industry-leading stat.

For context (excluding the Columbia re-entry failure), the space shuttle only had 4 nines:

0.99994^125 ~= 124/125