That is quite the sweeping assertion. When I tell English speakers my Dutch language first name “Ward”, they do not even understand what I am saying most of the time. Don’t even get me started on my last name which uses vowel sounds they do not have nor would be able to link to the letters.
I am no Vietnamese speaker, but know a Vietnamese woman whose name is spelled Trang and she says you have to pronounce it like “Chong”. If I heard that while driving, it would be of no help to find the right sign.
Now don’t get me wrong, if you know the local language then sure, it can make sense, but that does not “just work” everywhere.