^^ Peaches, i totally agree with you on the background music. If they don't wanna spend the time to synchronize it with the lakorn, then it's better not to put anything at all.
Mayura is using their background music to try and cover any Thai audio that might of come up unexpectedly which they didn't block it out on time. They even put the background music over the theme/ending song too! It sometimes take them awhile, like half way through the opening/ending credits to realize that they need to TAKE THE BG MUSIC OFF!!