Really? Have you ever been stuck in line behind some young gal that has to fumble through her purse to find her debit card, swipe it multiple times because it doesn't work right, then keeps entering her pin wrong.
It takes just as long as granny does with a check book.
The difference is the situation you describe, while valid, SOMETIMES happens. Check writers nearly always slow the line down. World's worst are those who have to stand there and balance it out while everyone else waits.