Comment by giantrobot

Some types of launches to some classes or orbits have gotten cheaper. Not all launches to all orbits. I don't know if any commercial launch services can even do planetary transfer orbits.

In space everything is an orbital change. To change orbits you need to speed up and slow down, all of that requires fuel. Even using what are known as "low energy" trajectories that use a bunch of gravitational slingshots need velocity changes to adjust trajectories to get the right angle of approach to some large body.

Most commercial launch services focus on LEO because the secondary stages don't need to carry much fuel and their engines only need to fire reliably once to get into a stable orbit.

A planetary transfer requires multiple engine firings. That's much harder than a single reliable firing. It's not impossible but the testing and engineering is expensive.

A science mission often needs to beg, borrow, and steal to get built. There's one shot to accomplish the mission objectives. That's more expensive engineering and testing. Some mission profiles require specific planetary alignments with very narrow launch windows to boot. So there's a lot of expensive work made more expensive by a tight deadline.

The actual marginal cost of the rocket, fuel, and launch is a very small part of the mission cost. Halving the launch price doesn't necessarily affect the cost of anything else.

Starlink satellites are effectively disposable. If a Falcon 9 explodes or fails to get the second stage to orbit they're out maybe a few tens of millions of dollars. If a science mission has some mission-killing failure there's no funding for a do-over.