My wife always gives me shit for trying to use this. Any job that involves communicating things like names or worse, random strings of letters, should train their staff to use it. Remember that part of the design was specifically to make it easier for people with English as a second language(or not at all) to still recognize the letters over potentially unreliable radio.
My understanding is essentially Apple has enough money on hand and foresight of product demands that they can do things like tell a supplier that they’re going to buy everything well in advance and secure those deals before other manufacturers are willing to commit. Presumably, there’s nothing to stop Samsung from going to TSMC and saying they want to buy all the capacity for 2024, except that Samsung doesn’t feel confident about matching Apple’s sales volume on those upcoming products.
I’ve also heard Apple will also fund expansion of their suppliers when needed. If someone makes a thing that Apple wants but doesn’t have the capacity to meet Apple’s volume, Apple will provide what they need to increase capacity, along with providing commitments to purchase enough product that the manufacturer is taking on minimal risks from the expansion.