Sorry but have you actually used a SAP system. I worked at a company that spent $80m on a SAP system that was comically worse than the system that came before it. To the point that people left the business because it made their working days so unpleasurable. This same story has happened at multiple businesses I know. But it's sunk cost fallacy - once the CEO and board has endorsed spending $80m everyone's just going to pretend it's fine.

I’ve worked in shops that built enterprise software. It’s not that hard.

SAP and Jira are just not great software. They’ve got excellent sales teams, connections, and probably great support. That’s the key to getting user-hostile software into big orgs.