[avmich]

There are at least two arguments in favor of ability to keep Russian launches cheap(er).

First if mentioned in John Clark's "Ignition!", where he says that the Russian approach to bigger payload isn't the technology, but just the size of the rocket - with same low-tech as something smaller. So, in other words, technological edges aren't always translating into lower costs in this industry.

Second is Russian's technological edges with kerosene liquid fuel engines. Technologies are well-optimized, including costs, and are the primary used ones for Russian space program. Not solid rockets, not hydrogen - and comparatively little hydrazin-based rockets, at least by the number of launches.

[bonzini]

As an aside, solid rockets is perhaps the part that disappointed me most about "Ignition!". I guess it shows its age. Do you know of any reading about their development? Couldn't find much on Wikipedia...

[noir_lord]

Those are interesting arguments but there isn't any evidence.

[avmich]

Where is the evidence that SpaceX rockets are cheapest? Just because SpaceX says so?