Why is Bash everywhere (in most if not all Linux distributions)?

History (acquired not through research but through spending entirely too much time hanging out with Bell Labs people): In the beginning (if you consider the beginning to be Unix Version 7) was the Bourne shell. Steve Bourne was the first to show that the shell which controlled the user's interaction could be a user program and not a special part of the operating system. A historic breakthrough. The shell itself was relatively clean for scripting, but had no command-line editing or job control. …