You're showing your ignorance there, champ. Make is one of the utilities that's required by the UNIX specification,which means that each and every single UNIX or UNIX-like OS is required to make Make available to users in order to be considered an UNIX.
So to make this quite explicit, for starters each and every install of macOS ships with make.
Which would be why my projects use the “GNUmakefile” file name explicitly, even though e.g. I tend to write to POSIX sh where I can rather than following the “bash scripting” trend. I also remember seeing a project in the wild that had a separate GNUmakefile and BSDmakefile, presumably for similar reasons.
If you use only POSIX make syntax, great for you, but there's definitely a barrier compared to what a lot of people are used to thinking of as Make nowadays.
(This is also ignoring the part where “higher probability” at a glance refers more to popularity than to standards compliance, and I don't read the parent as implying being in an environment where POSIX/SUS compliance is directly related to the set of target systems.)
You're trying to move the goal post here.
The question is not which obscure feature is made available only by a specific implementation of Make. That's completely besides the point.
The point is that Make is widely available as it is a required component on all UNIX operating systems, and this means that any standard Makefile you might have is assuredly supported on any UNIX installation out-of-the-box.
Because make is indeed installed on all UNIX, otherwise they are not UNIX.