Urgency

Manufactured urgency is the most reliable tool in fraud, because it removes the time in which you would have checked.

That is its only job. Not to make the story better, but to stop you stepping away from it. The same works with threatened consequences, which are urgency in another form: the account closing, the fine, the police. If you notice nothing else, notice that. A genuine request survives you saying "let me call you back". A manufactured one has to stop you doing that, which is why it always has a reason why you cannot.