The Thai government failed to share information because they were not specifically requested and that is the most despicable thing I can imagine. It is much like a fire station failing to respond to a fire across the street from them because they did not receive a call regarding the fire.
Obviously, there has been little to no cooperation between the countries around this area but there were lives involved and a critical situation and the Thai government deserves to be criticized harshly over this. Trying to understand and pinpoint the answers to this situation will, undoubtedly, involve piecing together information from multiple countries and multiple pieces which can, hopefully find the solution to this but withholding information of this sort is indefensible.
Of course, the Chinese are believed to have done the same thing by many so-called experts which have appeared in the media. It is astounding the countries seem to have no sense of common decency.