and you can ignore any automatic emails telling you to report until you've been back in Thailand about 75 days. They don't account for you being out of country.
the early coms before live date said one extension in the lifetime, post live date the coms now say one extension per entry. But you still have to leave and reenter once a year on top of an extension to get a full year.
i'm on my 2nd 5yr licence, and have never had to produce my passport. I do have to produce a permanent address, which you need to get from immigration, they only issue those for people on long term visa's, ie 90 day+, a DTV is longer than 90, so you can go to IM and get one. The gov are giving 180 days, they wont put people in a position where you are illegaly driving after 90 on an IDP and home licence as you cant get a Thai licence.
You dont need a visa directly for driving licence as such. You need proof of residency which is obtained from immigration. Immigration will issue these if your on a long term visa or extension of 1, a DTV should qualify as its greater than 90 days and you have a permanent address.
i suspect he made the mistake of going to the VOA desk first, rather than going directly to passport control desk. A lot of first timers entitled to exempt entry do that, myself included first time. Usually they get sent directly to passport control as their country isnt on the VOA list. Unfortunatly for your friend, his is, and the VOA team didn't enlighten him that he didnt really need it.
agree extensions have traditionally been 1900 regardless of length, but in all the official announcements describing the DTV prior to those issued to the consulates, etc (with no price shown), they stated it was expendable for another 180 days for another 10k. But your right people will bounce twice if they want 365 days a year.
i believe you were partly right, and in line with the intention of the visa. Officially if you want to stay a second 180 days , then an extension does cost another 10k. To do the full 365 days, you have to leave and come back utilizing the multi-entry even after an extension, which makes it a bit obsolete. So most people will bounce twice a year and avoid the 10k extension.
the no tax mentioned, is if you only stay for the 180 days in a tax year. If you stay 181 or over, you will be liable for any monies remitted into the country for the whole year.