The Homebrew devs originally decided not to duplicate software bundled in macOS, and to build against what was already available. I could see advantages to this, but Apple often left us with such outdated stuff.
The original solution was to tap homebrew-dupes, then install your tool. So for example:
$ brew info bc ==> From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/bc.rb
Hey, wait a minute. The URL points to homebrew-core now. Has homebrew-dupes been depracated?
These formulae were those that duplicated software provided by macOS. All formulae were migrated to Homebrew/homebrew-core
Latest commit by MikeMcQuaid 3 months ago.
How about that! I approve of this.