I've primarily run into this problem on NYC-MCO flights, but it's occasionally shown up elsewhere...

I'll often intentionally book a flight with a meal indicated (if nothing else, an included meal saving me a trip to an airport eatery represents a savings of $10-25 depending on the time of day and how horrid the airport's prices are; it also affects my "what do I do on my layover" planning, or indeed "do I need a longer layover to make sure I can get something": If I've got two long-ish flights with a tight connection, the result can easily be a rather long day). However, in spite of a given meal (breakfast, lunch, etc.) being indicated on the website, I've had a few cases where the meal wasn't present. As indicated, this has been most common on NYC-MCO flights (I think I've drawn the short straw on this route three times) but I also ran into a catering screwup ATL-ORD in February and I think there was another case thrown in. I was actually convinced that NYC-MCO wasn't a meal service city pair until Monday morning (when I actually got breakfast!) given my drought there.

Some of this is probably down to DL.com having its head somewhere it shouldn't be, but (1) how much of a "known" problem is this and (2) at what point would it be reasonable to kvetch to Customer Service on this? "Catering screw-up" is something I'm inclined to allow for once in a while; it's the persistent indications of one thing while getting another that bug me.