In the 80s and 90s, GM sold the tilt steering wheel as an option. The vehicles that didn't have the option had all of the components for it except the handle. A wise "hacker" could install the handle himself instead of buying the option.
The economics are simple. The components are cheaper than the cost of building two different modules. You have to re-tool the factory, keep track of which vehicles have it, deliver the correct one to the dealer, and maintain two different components for the life of the vehicle (i.e. stock replacement parts for both, separate instructions in the service manuals for each, higher learning curve for the mechanic, etc.). And it should be obvious that you're charged what you'll pay, not what it costs.