from my experience dealing with nosy wouldbe-employers and being on an immigrant watchlist:

they don't believe for a second you don't use social media; and if you don't, then you did at some point, and they'll find it; and if they don't find it, then that's suspicious, because obviously everyone uses social media, so you must be a criminal, using some dark web social media. and then you get credit checked forty times, only for them to find you have no debt and thus no credit score, and then they just assume you're not a real person and call the cops.