> NASA pays the same price per seat in the Dragon as the Soyuz because they prefer not to fill up all the seats.
That is incorrect. There are now a maximum of 4 seats in Crew Dragon.[1]
While it's true that NASA had plans to take down 6 Astronauts in an emergency, 2 of them would have basically been strapped to cargo pallets. Not something NASA would engage in under normal circumstances.
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1. > After SpaceX had already designed the interior layout of the Crew Dragon spacecraft, NASA decided to change the specification for the angle of the ship’s seats due to concerns about the g-forces crew members might experience during splashdown.
> The change meant SpaceX had to do away with the company’s original seven-seat design for the Crew Dragon.
> “With this change and the angle of the seats, we could not get seven anymore,” Shotwell said. “So now we only have four seats. That was kind of a big change for us.”
Paying for a full-service crew launch service including ground handling for payload and crew, space suits, life support, docking, and retrieval of the crew/capsule on landing is very different than paying for kg of payload launched to orbit.
The latter has gotten significantly cheaper.
NASA's price to SpaceX for the crew missions also includes development costs of the capsule and suits because there wasn't one on the market available for NASA to use.
And above all of that, price to a customer, especially a government customer with a lot of specific requirements and paperwork, is not the same as the actual cost.
