I have worked in many government schools. The training you refer to us not the first year of employment but the last year of study. Totally different to what you are trying to maintain, and yes, I have asked. In fact I've seen the salary scales from Ajarn 1 to Ajarn 5.
Most 7/11 employees are on minimum wage. 12 hour shifts for around 300 baht a day. Not sure how you can equate more money for less hours. Many Thai teachers will only teach upto 4 hours a day and will go home after their last class instead of remaining until 4pm. Add into that the paid holidays it is easy to see teachers do far less hours.
There us a set curriculum, I agree. However, I have witnessed many methods of teaching said curriculum. Those teachers that prefer their students to be blinkered usually do so from choice. I have witnessed great teachers using their own style to great effect. I have also witnessrd lazy teachers that are happy to just go the course.
I know many teachers who find their job rewarding, both emotionally and financially. One can only get out if it what one puts in.