SpaceX could absolutely do it. They chose not to in order to focus development resources on starship. It’s all about opportunity cost. Also, you’d have to rede

SpaceX could absolutely do it. They chose not to in order to focus development resources on starship. It’s all about opportunity cost. Also, you’d have to redesign F9 somewhat. Starship has the fairing integrated with the upper stage, which reduces recovery costs. Starship’s booster also does Return To Launch Site nominally, which means you don’t need a separate recovery droneship (Falcon 9 does that, too, but to make the most out of every expended upper stage, it makes sense to use down-range recovery). The F9 legs are sort of complicated logistically whereas Super Heavy is supposed to be recovered by the actual launch site, reducing turnaround time and costs. Also, using methane means less coking in the engines, which reduces turnaround costs and maintenance. Lots of things like that you’d need to reengineer to enable $1 million launch costs, but it’s feasible for an MLV. Relativity is planning to do it.