Why was my 60 SETV visa application denied by the Thai Consulate in Hong Kong?

and I think the O/P was mostly wanting to vent and that any constructive stuff has already been said.

A bit of research before you went there would probably have saved you some stress. It's been well documented in this group that if you're asked for proof of funds when buying a visa from a consulate or embassy in SE Asia that you would need to show those funds by way of a bank statement. Also, given that printing of online bank statements is fairly easy these days, rather than reacting with anger (which serves no purpose other than to cause you to not get what you want) it might have been possible to just go and print one.

As for 'what's going on with the immigration system' there are many people who are living in Thailand on visas that are primarily designed for tourists, some of whom are working illegally as well. Tourists are people who go somewhere on holiday, then go home. This doesn't seem to describe your lifestyle. You are retired with enough income to live in Thailand. That's why it was suggested that you get the appropriate visa for your circumstances. That would be the 'retirement visa'. Oddly enough, the staff in the Thai Consulate are not telepathic and aren't aware of your stated financial situation, or the fact that you don't need to work. That could be why they a) suggested the Non-Imm O-A type visa where you would provide proof of your earnings and work status and b) asked for a bank statement that, presumably, would also show them that you are not working in Thailand on a tourist visa.

Whilst you seemed to be angry at their requests, they're just doing their job. If you had provided them with what they asked for, you would have got the visa you wanted. You instead chose anger as a response and walked away with nothing.

Different kettle of fish in UK because we're citizens things are easy until you get to Thailand

I have heard getting g first Vietnam visa is easy but they don't like to renew does anyone know if that is true?

Couldn't show her your online bank transactions?

Bank Statements have always been required and not cash. Next time be as prepared as you can, research and have as many documents and proofs that you can have to cover all bases.

First of all you visited a Thai Consulate, not Immigration. Second as the rule at every Thai Consulate if you have to show proof of funds it is always with bank statements, never with cash.