The complexity of software is an essential property, not an accidental one.
The problems are different.
But the nature of software is that the problems are always different. You never have to solve the exact problem that someone's solved before, because if software already existed that solved your need, you wouldn't have to write it. Writing software is expensive. Copying software is cheap.
Software is easy to make, except when you want it to do something new.
The only software that's worth making is software that does something new.