What is process automation?
Process automation is the execution of a business flow by software: recognising triggers, processing data, updating systems and involving the people concerned, following defined rules and with exceptions that go to humans.
Rules and parsers get you far: emails, PDFs and known document formats can be processed with them too, as long as structure and wording stay reasonably consistent. It gets expensive when formats vary strongly, free text has to be interpreted or content has to be classified. That is exactly where AI is the justified addition, not a replacement for clean rules.