Yes free OCR software itself is pretty simple and can run offline but if your accuracy requirements are high (for critical documents), different algorithms (typically proprietary) are needed and as well as fallbacks to contracted human labor for verification. At some level it makes sense to outsource to a cloud provider.
Yep I've had to employ this software to get things done before. Also OCR doesn't need a cloud vs. a beefy computer - I do a lot of that too.