The source code is used to produce the "resultant binaries" so unless you have a very strange definition of "quality" the OP has a very valid question.
Is it strange that, say, comments are stripped out of a binary? Or that the file names of the source files are not in there? These things are examples of aspects of quality that have no impact on the binary but make a big difference to the quality of the source.
Because the industry norm for consumer gadgets is short product cycles, with the production of terrible quality code that doesn't see much maintenance after the release. Most users won't notice.
Even a "quality" product like the iPhone was shipped with everything running as root and a mess in the filesystem (and that's for a platform that has been maintained since).
