These pronounciations are for the International radiotelephonic spelling alphabet, often referred to as a "NATO Phonetic alphabet". For numerals procedures vary slightly, and they've chosen IMO. The sounds are chosen to try to maximize the chance that two people who know this system, even if they don't speak any shared languages, will successfully communicate the symbols intended, so they're not about how you might pronounce these words in any particular place, but rather a plausible pronunciation everybody can approximate and understand.