The algorithms used by our software programs to increase the brightness in the dark areas of the frame are much more complex than simple "multiplication".
Multiplying the luminance of an image will make it brighter. Doing this locally will make a local area brighter.
If you think that this is done using "interpolation" and injecting noise, that raw converters "cannot and will not interpret all of those pixels accurately" I would hope to see some references, an explanation or similar?
I have written (simple) code for making a viewable image from raw sensel values. I do believe that I have some knowledge about the basic steps needed. I don't know the details behind the proprietary engines of e.g. Adobe, but if you do, please explain.
-h