The monarchy is (almost) completely separate from the political system. While many people might debate the pros and cons of the Conservatives versus Labour, UKIP or liberal democrats, very few question the role of Queen Elizabeth II.
In the UK, the monarch has the the right to veto legislation passed through the parliament but this right is rarely exercised. This is quite different to the US system where the president is ultimately in charge and has to fight for re-election every few years.
It sounds like the monarchy in Thailand has strived to maintain stability for the people in spite of an unstable political environment. This might explain why the people continue to believe in the monarchy in Thailand in a way which seems alien to anyone in the USA.
There are a ton of US news sources while there is less reporting on Thailand and it is hard to get nuance when you don't speak the language.
Even people who are native English speakers but are not from the US don't understand politics in the US.