Many API developers may choose not to use them, but they are absolutely there.
You specify the type by including or excluding quotation marks, and then for the types without quotation marks, you either include or exclude a decimal point to specify float or integer, and for boolean you use characters (specifically true or false). Arrays are wrapped in [] and objects are wrapped in {}.
JSON data as a whole is passed as one giant string because the REST protocol demands it. But once it's been pulled in and properly interpreted, there are absolutely types in the data.
In case you're making a joke: The people who don't type JSON are using controllers.
In case you're asking a serious question: the people who don't type JSON are the people in OP's image. They are technically using types, but that type is literally always string. They don't use integers, they don't use booleans. This is functional but may not be the best choice, depending on what kinds of data their system is supposed to handle.
When passing or storing data in code you usually have to specify what type of data is it. An int is an integer, so numbers, there's also boolean (true/false) and many others. There's also string which is just characters of any kind (for the most part) which pretty much makes it a catch-all, since numbers can be a string along with letters and special characters.
But to use a number as a number after it's been received as a string it has to be converted to an int, which means extra code, more effort, more failure points etc etc.