For the monthly option you need to show in your THAI bank account, monthly money transfers from overseas, you must also have a minimum of 12 months of this happening
I know personally many people denied because they didn't have the funds in for 3 months, also know people who had money in there just a few days and was approved, all at the same embassy
some people are just walking red flags, they look suss, or have a suss history, It's not like everyone is being shaken down. I flew home to australia once and was interrogated for 3 hours because I didn't have any bags, I think some people don't want to admit it but they look like they couldn't possibly have 500k in the bank
Not that hard mate, the immigration officer does not have all the information you presented in order to get the visa, believe it or not many people fa ke details such as bank records, even put thier names on births certificates for kids that aren't theirs, it's crazy what people will do to secure a visa, it's the immigration officers job to scrutinize everything otherwise what are they there for?