I don't know precisely how they are automated, but a pile of applications came in seconds after opening the position. I think I heard talk about online services that you can pay to do the bottling, but cannot remember the name(s). I personally know people who wrote their own bot to do this.
It looks like most applications are from real people, but impossible to tell without a deep vetting honestly. Malicious people running several "fake developer accounts" (for remote work, which is all we do) collecting paychecks until fired, or simply spying, is a known problem in the industry, but not something I have experienced first hand. Yet.