Women actually have quite a few more neurological connections between the right and left side of the brain which gives them the mental capability to multitask better than men. But just because someone is capable doesn't mean they have the skills to do so or that they are good at.
What annoys me more than the chit chatty women at checkout lines is the opposite, the woman can't even seem to keep one thought in her head. She's the one who waits for the cashier to ring up all the groceries, give her the total, and then she realizes that she has to pay. So she picks up her purse, puts it on the belt, opens it up, digs through it looking for her checkbook, finds the checkbook and pulls it out, asks for the total again, takes 3 minutes to write the check, then the cashier asks for her drivers license so it's back into the purse she goes and digs through that for another minute, pulls out the ID, and finally 5 minutes later is done paying. For crying out loud, she knows she has to pay so why does she just stand there waiting until everything is bagged before even getting out her checkbook. She could at least have the name of the store written on the check and drivers license sitting out!