A human rated vehicle would be much more expensive than one rated for cargo. And there are not many use cases for the vehicle other than rescue missions to the two space stations.
Their astronauts don't need rescue. Nor a human delivery driver to chat with.
If a "10kg to (& from?) LEO for $250,000 flat rate" OrbEx service existed, 99% of the initial use cases would be launching cubesats. After a while, some LEO satellites might be designed to use it for additional reaction mass and other stuff. Space stations could use it for time-sensitive scientific supplies and zero-g manufacturing specimens, and an occasional priority repair part.