The whole "open the door without looking" thing is somewhat alleviated - absolutely minimally so, but still enough that I feel obligated to point it out in the interest of absolute fair evaluation of what a shit story TKJ is - by the fact that Babs is expecting a friend from her yoga class to pick her up. Even folks who always check the peephole (and who doesn't, in this world of solicitors and Jehovah's Witnesses) will still blithely swing the door open ten minutes after ordering a pizza when they have reason to think they already know who's on the other side. (Those people, of course, don't live in Gotham and have never been Batgirl, so the issue still stands... just not quite as bad as it looks.)