Part of the problem is that 'the company' accepts this 90% downtime, but managers running standups are paid to maximize productive output of their staff. So yo

Part of the problem is that 'the company' accepts this 90% downtime, but managers running standups are paid to maximize productive output of their staff. So you'd be lying to your managers with the end goal of behaving as the company expects you to. This kind of internal tension is normal in lots of organizational structures. It's better if no one has to lie but it isn't (in my opinion) a disaster or anything.