I have no idea lol. If they do it is so low I have not noticed. There is an ATM charge by some banks for withdrawals outside home bank province but I am not charged this for whatever reason.
Take a look at Singapore for example. They will only process DTV for locals and those on long term visas. Similar there for some other visa types too.The Embassies have discretion on who they process. Take a look at "B" Visas for work. As an example as a British passport holder I have had them issued in Singapore and Phnom Penh. Certain passport holders ie Indian I believe, can only have them issued in India. Embassies have discretion. Maybe they do not want their staff doing extra work for little reward.
Once it all goes all eVisa this will be the way. Might even change to apply only in home country or where you have residence. Less work for Embassy staff.
I paid my 3BB yearly upfront and renewed it for the year too. Kept post-paid AIS for phone but I got that on a Wor Permit and to be honest could probably get a better deal.
You are the only one I have heard say that. Many I know on Retirement cannot get a post-paid account with AIS / True never mind on Visa Exempt or Tourist Visa.
Post-Paid Mobile seems to be difficult for some on long term visas such as Retirement. I got mine with a Work Permit but kept it with retirement visa. My internet was paid a year upfront on retirement visa for home.