I don't know what's complicated. I'm here on a 12-month non-O visa extension. I never have any problems. It might just be as I have the correct visa for staying. Those who try to live here on continual border bounces are bucking the system. It's not that difficult to understand is it? If a person wants to live here long-term just get the proper visa
There is no criteria for the visa which states you must be retired. The criteria is "over 50". There are zero checks carried out to see if you are still working, so go for it!
Banking is a bit clunky and bureaucratic in Thailand, can't do much online, you have to go a branch for some things, but I wouldn't call it a mess. Once your account is set up, the apps are easy to use, payment by QR code is very fast, paying bills online very simple, ATMs are located everywhere (although with the surge in cashless transactions in Thailand, the number of ATMs will probably decline.