There is a minimum amount of money required to enter Thailand. It is also a fact it is almost unknown to be asked for. What looks like has happened in this case the requirements have come up on the check in clerks screen at check in and she has asked for them. The requirements are entered by back office staff and are sometimes inaccurate too or out of date. Certain passport holders are also more likely to be asked regarding certain requirements.
Yes, difficult to get over a year from a Thai bank. Immigration in country recently let me off with just a years statement recently but I should have had 15 months.
There are dozens cresting content in Thailand on tourist visas, visa exempt and retirement visas. I have never ever seen any reports of anyone getting into trouble for it. The nearest is when people have done actual client facing work like acting as tour guides or drivers. They are the ones who get into trouble.