The iPads have missed expectation. The expectation was PC is doomed because of iPad. Now after four years iPads sold less than 200 million units. Compare this to several billions of PCs. The iPads are still a fraction of PCs.
Productivity software usually needs more ram and storage to run. I think one of the most important and widely used productivity software is MS Office. I also think the reason MS has not ported Office to iPad is 16GB iPad not capable.
This is one of the biggest mistakes Apple made in positioning iPad. iPads have much bigger screen than iPhones. They are more suitable for productivity. With productivity one generally needs more memory. Apple is steering many productivity users away from iPads.
As an example most US carriers charge $30/month for a 3GB data plan. But a lot of users use only several hundred MBs per month. They are overpaying. If there is a pay as you use data plan, they could simply pay the full price of iPhone first and save a lot money.
Smartphones are supposed to be used with data plans. This is mostly true with US carriers. But I suspect this is not true in a lot of countries. AI readers from other nations please confirm this. I suspect most of the cheap Android phone buyers are either without a data plan or with a pay as you use data plan. So a meaningful comparison is between iPhone and other 'smartphone' with data plans.