What is the mindset of people who ghost after scheduling an interview?

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This is something I simply cannot understand based on my common sense.
Why are there so many people who schedule an interview, say nothing, and then just don't show up without a word while I'm waiting?
And when I call, they don't even pick up..
Is it really that difficult to just send a single text saying they can't make it?
Or is there some specific reason for this?