Because you are always only the user instead of the owner with an apple device and software.

I understand and share your feeling, however I think OP question is interesting enough to deserve a more complete response. Trying to frame it another way:

Is that specific non-par feature voluntary from Apple or might them just didn’t thought about it yet? If that’s voluntary, what’s the logic that make them think it’s better for their business to not allow that feature?

From my experience apple tries very hard to remove or hide any feature it can, there argument is probably to not overwhelm user and simplicity

That’s a fair hypothesis. Thanks.

For do not disturb, you can: settings -> focus -> do not disturb has a section at the top for allowing specific apps or specific people.

But that does not bypass silent mode. Critical alert does.