Apple does not allow sideloading, and does not allow use of any other marketplace. Google does.
This is simply not true. For example Apple allows many companies to have their own stores: Person App . In education and business administrators can side-load their own specialty apps.
Microsoft sell to people who want to use computers without learning how they work.
What? Isn't it the opposite? Apple Sells Computers to people who just want to do work and not spend hours figuring out how to use the OS. Example, I have spent countless hours showing people how to do the simplest of things on Windows 8.0 / 8.1.
Apple's market share is dwarfed by Android's, but Apple's profitability makes the Android people look like peasants.
One major reason for this is that the Android market is inundated with very low-end Android phones. These phones are often underpowered and have very little storage. I work at a large public school corporation and have kids come to me asking for help on installing apps on their phones or asking why they can't load music or download games. The hardware just doesn't support it, which limits the app and content Android market.