What it comes down to is that the most basic thing I can do with the default install of any reasonable UNIX system (./configure, make, make install) is not possible on a Mac without a lot of heavy and opaque lifting.
If you call installing a compiler a lot of heavy and opaque lifting...
Ah, okay. I contend that Dell machines aren't computers because they rarely have green LEDs anymore, and surely all computers have green LEDs!
It is interesting to note that by your definition, Solaris, surely a highly traditional UNIX, was, for a long time, not a UNIX (it didn't ship with development tools).
Based on what you've posted,you'd have a hard time calling anything that. And I'm including AIX, SunOS/Solaris, HP-UX, etc.
What you want is a UNIX or UNIX-like OS that comes pre-installed with GNU-based development tools. This is a choice in configuration, not a definition of what UNIX is or isn't.
The main issue is that Mac is probably not the usual target system for these builds (in comparison to a mainstream Linux distro). And as such differences in the version of the compiler, the set of libraries, installed dev tools, etc. may lead to build issues. You might have to download a few more things or know to add or override compiler or link flags.
Even with the latest Ubuntu or Fedora distro, you still run into having to know that you might need to install dev files to get a build from source to work (recent example for me is pcre libs for nginx).
How do you really go about this? Where did you get your compiler? Where did you get autotools? My point is that OSX doesn't contain the basic requirements for bootstrapping by default anymore.
You install the 'XCode Command Line Tools' as provided by Apple, or one of a number of third-party packages.
Similarly, on many unices, you will need to install a compiler (and particularly autotools); they are not always part of a default install, which may be just as well.
Also, OSX does contain the basic requirements: install XCode from the app store.
I've gotten by with installing gentoo-prefix in a sub directory, but that is quite wasteful of space. A homebrew setup would be much nicer.