If it's pronounced this way, why is it written that way?

[Dilbertian]

I've just watched an advertisement for Hyundai. If Hyundai is pronounced Shinday, why isn't it written Shinday?

I don't mean words like Ikea, where the same letters have different sounds in different languages. If a word is being transliterated from a non-Latin alphabet, why not use letters that have those values? HY is not generally proncounced SH.

You really love MacDonald’s eh?

Yes, and in the US its nickname is Mickey D's, not Maccy's as it is in the UK.

My Hyunadi has a name 😂

Properly. The way they say it round here is like Towie/Estuary gone mad. And it isn't local dialect, we aren't in Essex.