We can see the origins of this becoming a problem on Ubuntu with Canonical adding stuff like the Amazon search and seemingly having no issue with bundleware as a means of monetisation.
On the other hand I'm surprised this isn't more of an issue on the Mac, since Mac (especially older versions) will allow installation of software from random sources which could include bundleware.
Is there something about OS X that makes bundleware more difficult to develop or is it just easier to monetise an OS X app without bundleware?