> Unlike SpaceX’s hangars full of reusable rockets, there’s no building with cameras, spectrometers, telescopes, and spacecraft buses—the core chassis of a satellite platform—lying around waiting to launch.

Not exactly, but communications satellites (and even more LEO constellations) are made in a steady cadence, what's left to do is to qualify the types of cameras, spectrometers, and telescopes for the various missions, and attach them to standard buses with modular power, propulsion and thermal management. It's much more of an engineering problem than a science one.