How did Thailand remain independent when burma/malaya/india/Indonesian/… etc get colonise by great britai?

The first answer is somewhat correct, but it took a lot more than opening trade and using tact. Thailand used to be much larger than it is now. Once upon a time, it included most of current day Cambodia, Laos and part of Malaysia. The Thai gave up the outlying non-ethnic Thai areas to the French and the British, and then brought it foreign advisors to organize the police, the post office, etc, etc, etc. A very pragmatic people, the Thai. by the way,Great Britain never controlled the Philippines, that was Spain initially, until the US stole it fair and square and squashed the nascent Filipino forces after throwing out the Spanish.