They might just want proof that you are in fact able to do this monthly and that they don't care. But I am certainly interested in what people with more knowledge and experience think.
Because people have families and obligations back home?
They spend a lot of the winter months in Thailand, and back home in the summer.
Makes perfect sense. And continuing getting a extension is by far the easiest for the older folks at least, instead of hassling with going to Immigration multiple times during the winter months.
But if it wasn't... It would be cheaper to just relocate to another province for a little bit and get it sorted there than pay that extortionate price.