You're incorrect. Thai Immigration requires onward travel within your period of allowed stay unless you have a long stay visa. The DTV is not considered long stay.
The TDAC is just an ARRIVAL card, there's no requirement to provide an outbound flight. However, if asked, it is a requirement to provide Thai Immigration with onward travel within the time frame of your visa
Actually the 'retirement visa' doesn't mean you're retired. A requirement is to be 50 or over, you can work outside of Thailand and still apply for a 'retirement visa'