In order to obtain the STV you need to apply for it in your passport country or where you are a permanent resident. You can obtain a tourist visa from any embassy (there are some restrictions though) and then extend while in Thailand. (You cannot obtain the STV while in Thailand though). As a uk passport holder you could also come visa exempt and get a 45 day stay extendable by an additional 30 days (45+30). Then depending on the covid situation the govt may extend the cannot travel due to covid extensions that give you 60 days extra, or change to a different type of visa while your here. Ie ED visa.
Immigration in Bangkok is not giving the cannot travel due to covid extension until you've exhausted the extensions your eligible to have on your current visa.
I never said anything about returning to Australia. Just said that people are taking advantage of the covid extension to not leave Thailand.
Yes Australia is doing something different then most other countries by only allowing a certain amount of people on each flight. But people are free to leave Thailand.
you can apply at a thai language school and get up to 12 months. who knows if/when they will stop these covid extensions... its making money for the gov't. but no one is really stuck here anymore. there are daily flights out, so people who say they're stuck are just not wanting to leave!
then you need to apply for your COE. you upload your visa. passport and fill out the COE application. you can then check the next day and if conditionally approved you upload your flight details and within as soon as 1 hour you may have your COE done for download.