Why doesn't America spell everything phonetically?

In another question, Aviator Tom draws attention to a dumb teacher who can't spell pterodactyl How can some TEACHERS be so DUMB? ↗

My gut instinct was the teacher wasn't English and just thought everyone spelt it the same as in his first language. Now I know here in sunny wales it can be spelt terodactil (but it's usually spelt the English way) so I did a bit googling and was surprised to find different spellings around the world.

But that got me thinking. America dropped the "u" from colour, favourite, honour, analogue became analog (which to the British is an unpassable turd). etc I'm sure you can think of more. They did it to make words more phonetic and easier to spell.

So why doesn't America spell pterodactyl phonetically? In fact, why doesn't America spell most English words phonetically. If you've dropped a "u" why not go the full hog and spell pterodactyl terodactil? Especially as America is more diverse than the UK it would make more sense.
Why doesnt America spell everything phonetically?
Why doesnt America spell everything phonetically?
Why doesnt America spell everything phonetically?
Why doesnt America spell everything phonetically?
Why doesn't America spell everything phonetically?
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