Oh, I completely agree with that. I'll never forget a particularly frustrating conversation with a client who refused to allow access to their database, because we were using 'open source code that anybody could have changed'. That sort of thing – banning open-source software from your systems – is silly.

However, you've got to consider the default-conservative attitude of larger companies. In Apple's case for example, the breaking point seems to have been GPLv3 - this was when they started reimplementing things like Samba and removing copylefted software. And that's because the GPLv3 represents a real business risk – aside from the direct patent implications, litigation under it is sparse, and businesses don't like operating in unsure legal territory!