OK, I see where you come from. But you don't get infected just by installing software.
Well, sorry for not being specific. You get infected by *running* infected software, be it installed or uninstalled. The thing is, in order to run software, you need first to *download* it.
So then, what you have to examine is the typical workflow of a user when he wants to download new software. In Linux, you normally do it from a "sandbox" of packages, which have been curated by the community. In Mac&Windows though, it is the job of the user to find the software on the web (or on the store, but this case we discard it because AFAIK nobody has sold infected software in a physical store), and this is where the majority of infections come from. If you deny this fact, this conversation ends right here.
The latest major security vulnerabilities were not on Windows though.
That is like saying that bitcoin is a failure because of the latest price drop.