The assumption that is made with all of the StackExchange family of sites is that some legwork can be done by the user (askers and answerers). Many of the questions that are too broad tend to be ones that - with 5 minutes of googling - could be narrowed down enough that they can be answered concisely and constructively.
Such as with your question that you have linked. Within roughly 2 minutes of Googling the clauses "API magnetic card reader", "API card reader", "Card reader programming", etc, I got thrown a menagerie of articles that could be scanned through and read, hopefully narrowing the information enough in my mind to give a concise answer.
From what I know, the StackExchange websites aren't meant to take all of the legwork the questioner should be doing and offloading it to the answerers, that's why "Where should I start" questions get closed regularly.
ADDENDUM: Also, looking further at the singleton answer that you recieved. When someone is fishing for more information, and/or most of the comments on the OP are comments about needing more specifics or a pruned idea, it's a good show that you might need to narrow the question down further. Again it isn't that "Where should I start" questions aren't good questions, they just aren't suited for the system that StackExchange has set up, and they tend to fall outside of the good question stylings that they have in place in the "user agreement".