It's pretty much RAW. Those races are the uncommon ones, some of which are fairly rare.
"Scattered among the members of these more common races are the true exotics: a hulking dragonborn here, pushing his way through the crowd, and a sly tiefling there, lurking in the shadows with mischief in her eyes."
"And there, well out of the sunlight, is a lone drow-a fugitive from the subterranean expanse of the Underdark, trying to make his way in a world that fears his kind."
And from the Uncommon Races section in Dragonborn.
"The dragon born and the rest of the races in this chapter are uncommon. They don't exist in every world of D&D, and
even where they are found, they are less widespread than dwarves, elves, halflings, and humans.
In the cosmopolitan cities of the D&D multiverse, most people hardly look twice at members of even the most exotic races. But the small towns and villages that dot the countryside are different. The common folk aren't accustomed to seeing members of these races, and they
react accordingly."
So there you have it. Even in the largest cities are people what aren't accustomed to the uncommon races. In the small villages they are rare. And this is for the PHB races. For the even more exotic races from the other books, like Tabaxi, they are likely to be completely unknown in the smaller towns and villages that PCs often enter.
Oh, and the bolded portion from the first paragraph even tells the players that they may not be able to play an uncommon race, as that race may not even be in that world.