It's a legit question. I moved to game development last year after spending 25 years in business software . I work for a mid-size team that's part of a large company.
I think the simplest explanation is that games are not so rigidly focused on some of things that make business software take longer. There's more risk taking, more short-term solutions, less testing, and more bugs. And that's ok, because games only have to be fun. They don't need to manage your bank balance or solve the world's problems. This gives game developers the freedom to be creative and just "get it done" in a way that's sometimes not possible with the constraints of business software.
Another factor is that game developers play games -- their game and others. This is not true in other industries! Mainframe database developers (I did that at IBM) don't use a database at home for fun. Nor do they test out every other database in their spare time. People who work on email are probably not passionate about email in the way that game folks are into games. So I suspect this gives a little more oomph to push through and solve problems.
