This has nothing to do with windows. Nothing prevents software installed in Linux (or Os X) from installing crap Firefox (or safari, or whatever) extensions.
However, for various reasons – a mix of cultural and economic I suspect – ridiculous hidden installations and other software showing a coldly calculated contempt for the user are a fact of life while using Windows, and are very rare indeed on other platforms.
It has a unified place where programs can list themself, but the actual un-installation is up to the program. And it has no unified method of checking if programs are up to date.