> What is to stop any software company from doing the same thing?
anyone who is writing software can attempt to put backdoors in
it, but the real key is what privledges the software has when
it is running in its production environment. It is very
unfortunate that PC operating systems like windows get used
in production environments, because whatever code runs on them
has acccess to everything on the PC - it could for example
delete all of the stuff on hard drives, talk to comm ports, etc.
Under the Unix OS (and all its various spawn) most software
can run without privledges, so that even if the developer puts
in a backdoor or other bad code, that code may not be able
to do anything bad because it will try to do something, and the
OS will simply deny it access.
Unix, of course, was a Bell Labs product, and was much used in
the phone network and related activities long before most other
businesses. So, if you use the right tools, and software, and
your brain, you can be somewhat proof against this kind of thing,
but of course nothing is perfect.