If mood is mood and food is food why isn’t good goood?

If mood is mood and food is food why isn't good goood?
If mood is mood and food is food why isn’t good goood?

Short answer: English is weirder than a bread beard. Longer answer: Modern English is a mix of Old English & Anglo Saxon (Germanic), Norman (French), and Latin, with many other loan words acquired through trade & colonies. No effort was made to standardize English orthography (IOW spelling) until Samuel Johnson’s A Dictionary of the English Language in 1755. “Mood” was often “mode” or “mod” until around 1600. “Food” was “foda” in Old English, then “fode” “fude” and “foode” before finally settling on “food” in around 1700. “Good” was, in Old English, “god,” “godum” “godra” and “gode”, and then variously “gowde,” “guyde” goud” “gowid,” etc., “Good” began appearing about 1400 or so. Take pity on anyone who has to learn English as an adult.