I don't think that you're and author of parent comment are talking about the same thing. Most of low-quality questions on SO that make you think that author is lazy and unqualified are not about trivia or API bits like that. They're about a medium-level task that could be decomposed into more elementary subtasks without the need to know anything specific about the language or framework - but the author didn't even do that.

Following your example, it wouldn't be a question about formatting a number. It would be a question where the user would ask something along the lines of, "how do I write an app that calculates user's effective tax rate?". If someone is not able to decompose this at least to the level of "take input, process it, calculate it, present output" and then ask questions about each of those individual steps, or linking them together - then, in my opinion, he is stupid. (At least in the field of computer programming.)