I don't understand why people are expected to buy more software on their phone then on their PC
But they DO! For a majority of PC users software is scary, many worry about installing *anything* as it could "break" their computer. They lack the savvy to recognize fake vendors and malware apps. Also plain software incompatibility is a huge problem for them to understand. Even if they do buy something, many cant even find where their downloads go.
Now compare this to a smartphone App Store. Your CC goes to one place, Apple or Google who they already trust more than random developers. Installs are single click, generally can't mess up th system and are easily removed if you didn't like it.
All stores are MUCH safer and comfortable for general computer users. This is WHY there are millions of apps, finally non-technical folks are empowered to try out and explore software largely without fear. It's been a huge experience for them and finally showing them the potential of computers that WE have been claiming for decades.
So yes, people most definitely do pay more for apps on their phones than their computers, and they like it that way.