Same reason people at home just come up to each other and start talking (which actually requires immediate response) even when the topic is non-urgent whatsoever, instead of leaving notes around the house.
It’s all based on differing conventions among people, so saying a call “demands immediate response” is putting your convention above others as the only true one.
In my family the convention is a bit different. A single call does not signal any urgency and so no one is expected nor obliged to answer if they don’t feel like it. A second call after the first one wasn’t answered implies importance. Third and more calls imply urgency and then emergency. If something is important or urgent and calls aren’t getting answered, a message is sent.
I like my convention. I also have slightly different conventions with some friends. I am also aware different people may have different conventions and I don’t hold mine to be superior or theirs inferior.
Conclusion
The Equifax data breach from 2017 stands out as one of the largest data breaches in history, impacting millions of individuals. It is the result of several mistakes made by Equifax:
That’s what happens when corps cheap out on IT security. Storing so much personal sensitive data and not putting in the work needed to properly safeguard it. Good IT is hard, but not impossible.