It is a realistic example. Restaurants run out of food all the time. The good ones will offer some form of compensation for the trouble/inconvenience - especially if you're notified after you've ordered that the selection has run out; not tell you "well everything is subject to availability" and tell you to piss off.

Do I think DL is "deceptive" when changes happen? No. I think most reasonable people get that equipment subs happen in the airline industry and are needed to keep a schedule. I don't think some minor compensation in the form of a voucher or miles is too much on DL's part.