@Aether low cost STILL usually is the selection criteria, because if the government office accepts a higher bid they will get protests and legal challenges from the losers, and attacks from the GAO:
NASA estimated that de-orbiting the ISS in 2030 would cost $1.7 billion.
SpaceX gave them a fixed-price quote of $680 million.
The closest competitor, Northrop Grumman, came in around NASA's estimate.
Sure, it would be great if we had a couple of other companies capable of competing with SpaceX. But the key here is scale, and SpaceX is creating its own scale with Starlink. It's not at all clear how another company is going to compete.