The rerason is, that the RAW RAF file is not an image per se. It is sensor data. To display it, the data has to be interpreted into an image.
This is done by a piece of code and takes a little while. Being interpretation, the result may differ between programs.
What you see in Windows is that the explorer or most editors shows you a low-res jpg which is ...
If there is a way to access the files on the camera using Windows/File Explorer, any camera specific problem is already solved.
How to script Explorer using .Net languages is a topic for ordinary (non-photo) stackexchange, and independent of what Explorer is exploring.