You’re using extremely arbitrary definitions. “like it comes from the nineties” is not a very valid way to define a textures.
A texture is (literally) numbers. It has a certain size and it takes a certain amount of memory. It doesn’t have a date.
Many games “from 2021” can have better textures because they have extremely different requirements of the details to show within a scene.
MSFS’s airports aren’t displayed on their own. They have to be displayed together with an extremely detailed cockpit or aircraft, which takes most of the budget because it’s always on the foreground, on top of the world around them.