Hello.
In case this is useful to anyone on a non O-A visa...
Someone got his multiple-entry non O-A from the Thai Embassy in London in Sept this year. Entered and left Thailand before health insurance became a requirement. He has re-entered Thailand recently but this time he was only stamped in for 1 month.
This is just another experience and an update.
I have the permission to show his visa. The writing in Thai basically explains that he does not have any health insurance hence the 30 days' stamp.
Best wishes!