Except population exploded also, and the only reason we could support such a population has been thanks to advances in agriculture (it could be argued that's not a good thing, as the larger population is helping fuck our planet up in other ways, but that's for a different thread). So there has been an increased demand for food.
However, there's only so much arable land on this planet. The planet is finite in size. So when basically the entire planet is already being farmed, you can't really add more farmers, so further efficiency is just leading to less farmers.
Software is not so finite. It technically is, as we only have so many servers or whatever, but we're nowhere near the upper limits of what all we can handle or the appetite for software that companies have (which seems about infinite). Additionally, we have a habit of rebuilding and replacing software every few years, so even if we reach capacity limits, there's still demand for new software to replace the old, or working on new features for existing software.
So it's a bit different of a situation and not really comparable.