Why every sentence ends in ครับ or ค่ะ

Thai has no 'please', no 'sir', and no polite verb forms. All of that work is done by one syllable at the end of a sentence: ครับ for men, ค่ะ for women. It signals 'I respect you and I am being civil', which is why Thais use it with taxi drivers, waiters and bosses alike. Leave it off and a perfectly grammatical sentence sounds like a command. Women have two versions: ค่ะ (falling, for statements) and คะ (high, for questions). The particle is tied to the speaker's gender, not the listener's, and transgender Thais choose the one that matches their identity. Alone, ครับ or ค่ะ simply means 'yes' or 'I hear you'.