Not every country even uses Latin alphabet. That’s for one. And you wrote “such alphabets” whereas OP specifically named NATO one. If each country would have their own implementation it would be even more effort consuming and wouldn’t solve anything beyond what we already have.

This is mostly fine if only done for ambiguous letters and if the understanding is that it is done to reduce ambiguity. There is a contingent of people who painstakingly spell out every letter with a phonetic from their own system and it requires the listener to do a lot more decoding to the point of actually increasing ambiguity. "My name is Michelle that's M/N as in Nail/Mail! I as in Icecream! ..." Nichelle is confused about why we use words to spell out certain letters.

Same, but once every 2 years. Just email me for goodness sake!

Some good advice I got from a HAM was to read license plates in your head using the NATO alphabet. Their letters are mostly random so you tend to see each letter at roughly the same frequency and it can be done daily without taking away time from your schedule. Being random also prevents you from just remembering the order of the words and actually associating them with their respective letters.

After doing that for a week or two (I was bike commuting at the time), I had it pretty much memorized.