You might be right. Still, it may have to do with the strength of 'wanting' and 'willing' in English. Thinking of my native language (Dutch) I'm pretty sure 'vil du' would almost always be translated as 'do you want'. Never thought the amount of wanting, of will could influence the translation of the word.
Perhaps it is because the time in the original sentence is composed of words, and Duo expects the written form in the answer. One more thing: the 24 hr. time notation is always written with four digits, making three o'clock AM, = "03:00". Military time notation often incorporates a letter as an end suffix, to indicate various time zones.