I think that is a question that a lot of people would like to have an answer for. They have their own engineers design the raw format, and I believe they are convinced that their format is better than any other company. Really, though, I don't think there's an answer to your question. Adobe developed the DNG format as a common alternative. But only Pentax and maybe one that the company has been willing to adopt it as an alternative format. The solution, just deal with it.
What are you talking about? Whenever you shoot a raw photo you have the file on the camera memory card.
The raw files are not secret but what the camera manufacturers do to the raw data to convert it to a JPG is secret so Adobe does their own rendering, which is also secret, their intellectual property.
What I find amusing is that you feel justified in posting this question here instead of addressing the camera manufacturers on their own turf.