On your second question - as an enterprise software developer and hobbyist game developer of ~8 years, I'd say they're complex in different ways...
ERP software is mostly a giant CRUD app/database, with APIs, reporting functionality, and a ton of relatively simple code for automating the system/business processes attached to it. These parts taken alone are usually fairly simple, however the complexity really stems from the enormous scale, interfacing elements, moving requirements, and mutability of everything. It’s easy to knock SAP, but it’s difficult to keep software nice when you're dealing with these attributes.
As for game development, I tend to find it more computationally complex, but that can depend on the game and tools you use. By computationally complex, I mean the code itself is generally more complicated. However, what’s easier in game development is the amount of control over things you have. In comparison, you largely dictate how much mutability your game will end up dealing with, the data it will use, and how large the game will be. Players aren’t going to be dictating this. Not to say game development is easy, but it’s easy to make slick software when you have complete control over the nature of things.
So in short, ERP software is complex (and crappy) mostly due to the enormous scale and the complicated nature surrounding the software - whereas games are complex in regards to the nature of software itself.