As Chris states it was supposed to be a pilot program for Australia for six months first and after include all the countries entitled to visa exemption. But it’s delayed.
It’s still formally a requirement on tourist entries to show proof of an onward ticket within the days you’ll get stamped in for, proof of accommodation and 20K baht or equivalent in cash. Your experience only tells that you’re personally aren’t asked, -not that it’s still isn’t a formal requirement. This has nothing to do with TM.6. Even in this tread you see people have different experiences and it don’t help people who have been denied boarding and even de-boarded on a three legged flight regarding this.
Always best to apply for a regular 90 days Non O at home before you leave. Then you can open a bank account and apply for one year extension of stay within two months.
If you come on the Non O-A, you’ll maintain the mandatory thai health insurance requirement for all future.
The requirements for to apply for the Non O at home or in Thailand are the same. But at home you can apply just with income min equal to 65K baht or funds equal to 800K baht. In Thailand you’ll need to bank 800K baht in a Thai bank account for to apply.