Yeah so as he says WinOLS is really beyond 95% (or more) of tuners. Generating definitions from scratch is extremely time consuming. For example there are 165 operating systems from 2002 to 2016 in the Ford Falcon. Each of these has to be defined separately. We have written our own decompiler that pattern matches several calibration that we have defined by hand against all of the others, this makes the process much faster, but you still have to write the decompiler. There is probably 2 years full time work that went into just that one part of the software.
Basically this job gets harder each year as PCMs get more complex, different security (and checksums) and they add more and more advanced algorithms and tables. The current 2018 Mustang for example has over 33,000 scalars and tables. This is a compilation of 100s of engineers work over 20+ years. It is not really possible for one (or even several) people to reverse engineer and understand all of this. Sure you can reverse engineer and define the tables, but how they all interact and work is incredibly complex.
Even calibrators who work for large OEMs who have access to source code and calibration guides struggle to understand how a lot of it works at times. This is simply because of the vast amount of code that needs to be understood. Often you'll have a full team of engineers, each working on calibrating only one part of the PCM, they often don't understand what the other ones are doing as they don't have the time to learn everything.