I'm going to have to ask my boss if we can post a notice saying "Depending on the number of customers, employees cannot assure that your purchase will be gift wrapped 10 minutes from the store closing time". (that's a bit wordy but meh).
See, I do gift wrap in an upscale department store. It takes time, even if I'm the faster wrapper I still can't work magic, something that some customers seem to think.
If you show up 4 minutes from closing time with two huge boxes, we're going to tell you it's not possible. (we're not paid overtime, we've already had a long day filled with some bad customers, it's 8pm and we just want to go home. I'm not sure we're actually allowed to work past the store closing or that the customer can be on the premises.)
Moaning "they should put a notice that gift wrapping won't be available 15min before the store closes" " will get you a "from what planet are you from" look. It's 7:55pm, what on earth were you expecting?, at 7:45 we would have done them (well, not that day, we already had a customer with multiple gifts to do).
We get some reality challenged customers, thankfully very few who gets nasty with us, but the ones that get surprised that their 25+ boxes will take a while to wrap, or who asks us to wrap three boxes together but they don't match one way or the other (3 different heights, widths, lengths...) and are puzzled when we tell them it's not going to be possible, are meet with a "we're not actually Santa's little magical workers"* look.
*That's the nice version of the thought, people working in retail or with difficult customers will know what we really think deep down.