Why heterosexual think we want to date every gay on the planet ?

I mean, when a heterosexual says to you : look there is a gay overthere, don't you want to date Jul ? the gay : nah don't wanna. The hetero : why ? You're gay no ? Why they can't just think 2sec and réalize that we also have standards. For them it's like we don't have standards or that we see a gay once a year ? I dont' understand