My first job interview went like this. They had a specific problem that they wanted to solve, and asked me how I would do it. I gave my answer (solving the problem for them), and they offered me the job, so I got to spend the next six months implementing my suggestion.
I had a rather lengthy interview process for a one time contract doing some technical documentation. I explained what docs I would provide, how they would be organized and an example of the main docs being used. They ate it all up, and decided to use my stuff as templates using current staff after offering and then rescinding the job.
At the time I decided against pursuing any action against them because I wanted to look ahead to the next opportunity. In retrospect, I should have billed them for my work which they were using.
Except that I've seen it happen. The only thing I can think is that all the costs you describe are pushed to another group in the corporation.