And the only time I've encountered where it's not Ctrl+C in Linux is in the terminal. That feels like a reasonable exception to be grandfathered in, given it predates desktop environments. I will definitely grant that being able to Cmd+C/V in terminals is pleasant though.
That is a very strange keyboard shortcut when the home and end keys exist though.
Edit: It seems that Ctrl+A actually moves back to just after the most recent newline. That is not the same thing as moving back to the start of the line.
What's the difference between "just after the most recent newline" and the start of the line?