Ever wonder why those scam emails you get are so badly written? Well, it turns out the scammers are well aware that they have two ways to be wrong, and they’re attempting to limit false positives….aka those who take up their time without falling for the scam.
Those who are oblivious to or unconcerned by the typos might very well miss other warning signs later. Given that the base rate of those ever willing to give them money is probably quite low, they get far more concerned about making sure their time isn’t wasted than catching every possible mark.
For more on selection bias see here.