Some people don't realize the enormous responsibilities involved with administering a large social network site. Basically, a social network site is just a large website. It doesn't take very much capital to develop one. All it requires is hosting space on web servers that host a bunch of html files, along with the necessary administration and development.
Today's sites require minimal user authentication. Anyone can go online and open an account and fill out a profile. The companies which own these sites need to be very straight and operate with the highest ethical standards. Some form of advanced user authentication for account holders should be required, such as facial recognition.
In the more developed countries, at least, there are numerous databases with personal photographs. The pictures don't even need to be that current. Most PCs and smartphones have cameras. Someone would just need to upload a photo when they're opening an account, and the site could cross it with its database.
Unless something like this is implemented, the source of information as conveyed through a social network account is uncertain, and the reliability of information is undetermined.