There could be an endless amount of reasons why PCs get so many more viruses than Macs. I think it's a scam, personally. I owned my very first MacBook from 2007 until 2013. I had no issues with it and the MacBook Pro I got to replace it works like a dream. I will never, ever own another PC.
I know that people have issues with Macs because there is a learning curve if you grew up with or work with PCs constantly. You get used to something and you don't like change. Macs are expensive, but they last forever. PCs are cheap, but they don't last as long -- mainly because they get unfixable viruses.
No matter how much anti-virus you put on your PC or how many times you run a cookie clean up, a PC will inevitably get a crippling virus.
I'd like to think Macs don't get viruses because of how expensive they are. Maybe they have some serious anti-virus installed that can't be cracked...
As for Android and it's issues, I also went from Android to iPhone because my phone got a virus. I will also never own an Android phone again. Smart phones are just mini computers, how would they not get viruses as well?