@Graham *****
but it really doesn't due to the seasoning requirements.
Come in on a 90 day Non-O and you have less than 30 days to open and fund your bank account, probably more like 21 days in reality. This is due the requirement to have the money in your account for 2 full months (not 60 days) before the date you go to apply for the extension, I'd never recommend running this to the last possible day.
If you come in on a tourist visa, which you can extend for 30 days you have more like 75 days to fund your account. This is because in most places you need to have at least 15 days (a couple of places are 21) left on your current stamp before applying for an in country Non-O visa. There is no seasoning requirements for the funds for the initial 90 day Non-O visa (unless you're unfortunate enough to be in Jomtien which does require 2 months seasoning).
So in summary you get much more time to organise bank accounts and transfer money with a tourist visa