Facebook has 1B+ people. Do you know how trivial it is for them to run surveys? 100K population surveys, if they want? Many hundreds of them, simultaneously?
I have no insight into how facebook manages its surveys, but I'd be surprised if they didn't have some sort of generalized surveying platform built in to facebook that allows product teams to independently survey more or less anything they want.
Why do you guess that? Facebook could get a very accurate assessment of user opinion by surveying 10000 users. If Facebook has over a billion users and surveys 10000 of them, then the probability that I personally get surveyed is tiny, and even the probability that anyone I know gets surveyed is pretty small. So the fact that Facebook didn't survey you or me is not a good reason to think they haven't been surveying their users.
You have no knowledge of the surveying process, it is presumptuous to assume that they carried it out incorrectly simply because you were not surveyed.