I suspect, but certainly can't prove, that there are two things going on... first that in order to get reasonably true answers to questions you have to provide

I suspect, but certainly can't prove, that there are two things going on... first that in order to get reasonably true answers to questions you have to provide a fair in-kind trade with the user. If you want their home location you could ask for it, in which case a lot of people will seem to come from zipcode 12345, or you can offer a solution to a problem (or preferably a set of problems) they may have that is easily solved with their correct zipcode such as "lists of X within a mile of your house." That's a bit harder to pull off when it's something like "what political party are you?" for anyone who isn't rabidly political. The second suspicion that I have is that this is a result of a larger conceit of the tech industry that they are an enlightened minority who either know or can know better than the masses (tech isn't unique in this conceit, alas).