Most fast food restaurants have a separate category for kids, usually for those that are age twelve and under, in which they offer kids' meals and many sit-down family restaurants also offer kids' meals. I would assume that restaurants offer akids' menu for a variety of reasons, such as to make therestaurant more affordable for families, to appeal to kids and their simplified tastes, to bring more families in because there are reasonably-priced kids' meals, and to match what the competition is doing. None of this is especially surprising or earth-shaking, and there are probably some families that stretch it a little bit in regards to the age requirements, but all-in-all this formula appears to work out for everyone involved.
However, I later discovered that some people, usually female, like to occasionally order the kids' meal for themselves. The simplest way to do so, is at the drive-up window, in which quite frankly, it seems reasonable to order a kids' meal to go and even if the restaurant was to suspect you of really ordering it for yourself, there isn't much that they would want to do to preclude you from doing so. In regards to sit-down family restaurants, this issue is far more problematic, to which some restaurants will simply allow you to order off of any portion of the menu, as a matter of customer retention and satisfaction, and others are fairly adamant that if you are not a child, you aren't going to be able to order off the children's' menu.
Is it wrong to order a kids' meal for yourself? Basically, there are three thoughts on this. First off, most restaurants make it clear that this is age specific, and if you are not part of that age demographic, it seems pretty obvious that you shouldn't be able to order from that menu. Secondly, there are woman that aren't all that hungry, they are petite or perhaps even in a hurry, and consequently it isn't so much that they are trying to "get one over" on the restaurant as that they would prefer to be allowed to order only what they feel that they can eat in one sitting. Therefore it then follows that for certain people, since there isn't a half-size option for an adult meal, that ordering an adult meal simply doesn't make sense and/or would become a temptation for them, because of dietary concerns, or calorie counts, or the like.
The problem for restaurants, though, is that the kids' menu is primarily there as an enticement for adults with their families to frequent the restaurant and to help increase business as opposed to the restaurant being built around kids' meals and their much lower selling price point. For the fact of the matter is the profit margin on kids' meals is considerably less than for adult portions so most restaurants would be displeased if too many adults consistently ordered kids' meals for themselves.
While it is clear that adults are not kids and consequently do not qualify for purchasing kids' meals for themselves, in this era of entitlements, some adults with our without a good reason, will do so.