Usually, you don't lose a customer over a bug in two days. Customers are reasonable usually and understand that it takes time to fix bugs. Most of other reasons like CEO doing a demo at a conference can also be managed. I really don't see a reason for hard deadlines ever. In fact, hard deadlines is sign of bad management with notable exception of startups and other young companies with no managers or new managers.

Sharing the reason allows for that debate, or alternatives. Maybe the customer has some sort of demo or something, and you could offer a workaround in that case.

Hard deadlines for some sort of fix or workaround do exist. Like "Earnings Call Tommorrow, and I can't just say ' I Dunno'"

I agree with statement "Hard deadlines for some sort of fix or workaround do exist". Key being get this done before CEO's big presentation or hard code something or CEO doesn't demo this feature. The point is no one dies if CEO doesn't demo it or feature is not complete by earnings call. Earnings call is known event, one should have better planned for it.

And that bring me to people literally dying because of bugs in software like in cars or medical devices etc. That might be one time where I would have no problem sacrificing my family time for getting bug fixed. But most other situations are just artificial and deserve no extra stress.