You are right and it's a complex matter for people working and travelling, however as this is a forum mainly for expats living in Thailand and who are probably here fulltime, there is no argument, if you are out of the country for more than 183 days in any year, you will be classed as a non-resident for tax purposes - end of story irrespective of how much you cry about it, ignore it, or think differently - - end of story.
As I've said previously, I doesn't affect me now - but I'm dead against it for the average pensioner who lives overseas.