Oh, it's been solved, many times. But consider the advantages of paper:
- low battery usage
- high contrast; easy to use in direct sunlight
- rapid bootup time
- you drop it, it still works
- cheap
- low training time (for simple forms)
- error-tolerant in many ways
Now, there are problems as well, for sure, like no data validation and expensive harvesting of that data. But, in many cases, the above advantages outweigh the disadvantages, not because there's not good software to replace it, but simply because there are things that paper is very good at. If you don't particularly benefit from the advantages of software for your exact use case, paper can be absolutely the correct choice.