Because to Apple once you open a terminal you leave the supported world behind. This is a standard thing for them. Apple is not really a UNIX vendor and certainly not a Linux vendor: they sell macOS which is primarily a consumer OS and has its own APIs for everything.
Tools common on Linux like curl and git come with the OS basically for developer convenience. Apple doesn't write those programs, they don't use Apple's APIs or platform features, and thus in some sense you aren't really meant to use them in Apple's eyes. Ports of UNIX CLI tools exist in a kind of semi-supported netherworld on macOS. They run but they aren't fully integrated or supported parts of the OS.
Tools common on Linux like curl and git come with the OS basically for developer convenience. Apple doesn't write those programs, they don't use Apple's APIs or platform features, and thus in some sense you aren't really meant to use them in Apple's eyes. Ports of UNIX CLI tools exist in a kind of semi-supported netherworld on macOS. They run but they aren't fully integrated or supported parts of the OS.