Is it surprising to people that non-democratically elected leader to be loved? You have to remember that Thailand is an Asian country with Asian cultural beliefs and perspectives. These differences resulted in our inherent respect for elders, supervisors, rulers, etc. And our strong belief in hierarchy as opposed to meritocracy. These demonstration of respects would hold for people that you respect regardless of legal precedence. It is a bit hard to describe these actions in Western context. But with growing Western influences, these views have slowly altered closer to a Western one.
Generally and historically speaking, the public have been more or less given one-sided information on the institution on what good the King and Royal Family have accomplished on the behalf of the country and its people. There's a long list of accomplishments such as New Theory of Agricultural
Generally and historically speaking, the public have been more or less given one-sided information on the institution on what good the King and Royal Family have accomplished on the behalf of the country and its people. There's a long list of accomplishments such as New Theory of Agricultural Development, rural irrigation projects and community development projects. Not everything that he supports are perfect. There are areas that haven't worked out or could use modification given that technological advancement and unintended consequences due to lack of knowledge at the project implementation.
These publicized projects could be taken as propaganda. Some would that as genuine hard work on the behalf of the people. In hindsight, it's probably a combination of both. How the palace with the help of US government in projecting a hard working king to help the people. The publicity and tangible accomplishment helps propelled him to status of respect and beloved by a large majority of the population.
This publicity campaign was also helped by the Lèse-majesté law which makes insults and threats to the King and two other members of his family illegal and the offender could be punished by up to 15-year imprisonment. This bring us to the dilemma of his supporters being able to voice their support while his detractors would not have the same level of publicity for their narratives or how far those narratives can go. Criticisms of the law is that it is a criminal charge, the cases are trialed under closed door due to repeating the offending statement would also constitute LM as well, and how the charges can be brought by anyone. To date, no charges have ever been filed by the royal household on anyone. In 2005, the King gave his annual birthday speech that was interpreted that he suggested LM should be changed. LM can be changed through parliament. Parliament are also protected by parliamentary immunity. LM could be changed by parliament enacting changes to it. Recently, a group of academics have proposed to the current government to make the changes. But no parliament have ever proposed or moved to change LM. It has become a political tool for power players as well.
In recent history, the political forces have changed. A brief history of these events are heavily reported. It can be summarized as a political tension between the military and Thaksin Shinawatra's supporters. Thaksin was first elected into office in 2001. On his first and second term of office, he has been accused of corruptions, his handling of the southern Muslims and his war on drugs that lead to over 2,000 deaths. Large protests of thousands gathered in Bangkok to force Thaksin to resign from his post. He never resigned. In 2006, a coup was staged by the military. At the time, the coup was considered popular with poll showing that it received high supports among the public. The King was perceived to be approving of the coup due to his televised audience of the coup leaders. The popularity of the coup has since eroded. The military-installed government came into power and wrote a new flawed constitution. That pretty much sums up the military government accomplishment. After the military government stepped down and a new elected government came to power and the elected government was a Thaksin ally. PM was found by the court to have received payment from his appearance in a cooking show which was considered illegal. A new government was elected and Thaksin's brother-in-law became PM. Protests still continued and the party was dissolved for election fraud. Thaksin was also found guilty of corruption. He maintains his innocence and said that the charges and convictions are politically motivated.
Military has ties to the Royal Family and the Democrat party have aligned itself with the military. As for Thaksin's camp, they have implemented strong populist policies that have benefits the rural communities which are mostly poor and haven't been included in the previous political movement as much as they have participated before. Accusations of widespread corruptions by all sides have been thrown. Most recent clash was when Thaksin supporters and others demanded that Democrat government resigned because they do not believe that the previous administration have the public mandate to govern due to parliamentary motion that they came into power with. It lead to month-longed sit-in at central business sector of Bangkok in 2010. It became an armed conflict between the military and the armed protesters. That resulted in 98 deaths over a 2-month period.
So overall, his public support would be strong and respected. As mentioned aboved about the current political mess, his support might has dropped but there is no poll that have ever been conducted on this issue and the sensitive nature of such polls would cause.
This has been edited from the initial answer to reflect some additional information and added context to the narrative.