I am a lacto-ovo vegetarian with an annoying tendency to forget to book vegetarian meals when I go flying. When I forget to book ahead, I always ask if they happen to have an extra veg*n meal, but quite understandably they never do: they have precisely what has been pre-booked and nothing more. Which makes sense.
Whenever I do remember to book a veg meal well ahead of time, I always specify lacto-ovo vegetarian (i.e., with milk, cheese, cream, eggs, etc., just no fish or meat) if I can.
Despite this, I don’t believe I’ve ever actually been served a lacto-ovo vegetarian meal on any flight I’ve been on: the meal served is invariably vegan, despite me booking it well ahead of time as a lacto-ovo vegetarian one. Personally, I find this a bit annoying, because it means pretty much everything gets switched out for beans, rice, raw fruit, and crackers. Everyone else gets yoghurts and cakes—I get carrots and apple sauce. Boo.
I realise that the airlines don’t make the food themselves and have little control over what the dish of the day will be on any particular flight on any given day, but the fact that they do generally explicitly offer the choice between different kinds of veg*n meals would, I assume, imply that Gourmet Gate and similar flight meal companies do make these different variations of meals. If the companies that make the meals only made regular and vegan, there’d be no reason at all for the airlines to ask for any more details.
One also presumes that it would be very easy for these companies to make gradations. A lacto-ovo meal, for instance, would generally just have to switch one component (the meat in the main dish) for a veggie option, which my limited understanding of how meal factories work leads me to believe would be simpler and cheaper than a vegan meal where more or less everything is substituted. True, it would require some additional start-up cost to set up an extra packaging combination, but given the quantities of food these companies make, this extra cost doesn't seem like it ought to be prohibitive.
The way I see it, there are two basic tenets here that work against each other for the airlines:
- Offering a broad variety of dietary options is good PR and customer service
- Having to pay for a broad variety of dietary options is bad for business
Obviously a compromise between these two must be found. That is a given.
I have, on occasion, come across airlines who sacrificed customer service for business in this context and basically only offered a regular meal and a vegan meal. No other options. That's understandable and consistent, if not particularly satisfying for the customer.
The vast majority of airlines, however, seem to basically try to avoid the compromise altogether: they offer a full deck of dietary combinations, but once you get on the plane, they only actually provide regular or vegan.
To me, this seems to be a very strange decision. As a customer, I may be a bit disappointed to be told that I can only choose between regular and fully vegan, but at least my expectations are met. I am definitely going to be a lot more annoyed to be told that I've successfully booked a lacto-ovo meal, only to be given something different when I'm on the flight.
I have limited experience with halal, kosher, etc., but the few times I have travelled with people who booked meals like that, they have gotten special meals—not vegan ones. Conversely, as Itai mentions in the comments, lactose-intolerant people generally get served the vegan meal as well, and I've seen gluten-free bookings go the same way.