I don't think it's a generation thing, I think it's that what we generally consider normal has changed, but that some people got left behind in the old normal.
I’m saying that if two people have each other in their contacts lists and are on friendly terms, it’s not rude to call them if you need to talk to them.
Maybe I misunderstood, though. Sounds like you were talking about cold calling someone you don’t know. I agree that’s rude if the person is not expecting random inbound calls or isn’t in a professional context were there’s an expectation of receiving a call, and has been for generations.
And, obviously, in a work/professional/commercial setting it's always OK to call if they've given you their number. It feels weird, but it's OK.
Isn't that the definition of a "generational thing"?
Now I have to think every time, is this someone I have to text first? Or do they consider texting then calling redundant? Anyhow, I think both are important communication techniques, adults should be able to do remote direct verbal and async written.
Delivery Drivers/taxis use their own phones to tell you if their arrival times will change.
Medical calls can come from personal phones.