I explained before. But in simple terms.
It's is easier to make a tabaxi history, culture, and stats feel interesting and diffrent from human's than it is to make wild elf history, culture, and stats feel interesting and diffrent from wood elf, high elf, sea elf, dark elf, etc.
Ican do a lot more with a "cat-person" than "another type of elf or dwarf".
Not that it's impossible. But most DMs who go that route don't go that deep. They don't have the passion to do it. And they don't tend to want players to adjust the core of the races. So these outside subraces end up really shallow.
Yeah. As a general rule you get three types of elves, one or maybe two types of dwarves, and one (or
maybe two if you're
very lucky) types of halflings, at absolute maximum.
For Elves, it's Haughty Elves, Hippie Elves, and Punk Elves (evil optional.) Dwarves are either beer-swilling physical warriors and/or laborers, or (if you get a second archetype) soft-handed, highly-educated, rich noblemen who are the ones that employ the previous type. Halflings are either English landed gentry or rough-and-tumble commonfolk (usually only one or the other, but occasionally you get both.)
Humans you usually get somewhere between three and six types, which are all real-world cultures with the serial numbers filed off. Celts, Romans, Arabs, Vikings, an amalgam of India/China/Japan, or pyramid-builders (which may be Egyptian, Aztec, Mayan, or a few other options.) Alternatively, the setting leans extra hard into nearly-explicit European analogues, and you'll get a Venice-like merchant "republic" (that is actually an empire), a
very glamorized HRE, a Papal States type theocracy, the Celts again, and sometimes analogues of medieval France and/or the Umayyad Caliphate.
And yes,
lots of people rely on these really quite staid stereotypes without delving into them any further. The
Belgariad, for example, is practically
built out of tropes like this.