A lot of companies choose to keep their intellectual property as "trade secrets" instead. (Like the Coke recipe, etc.) Just like SpaceX, it can often be better for the company than a patent.
This is why Boeing and Lockheed had to play nice and form United Launch Alliance for the EELV & Space Shuttle Support Contract.
http://www.globalsecurity.org/space/systems/eelv-program.htm
They formed United Space Alliance (USA) for the Space Flight Operations Contract.