Eating Out Isn't an Option for Big Families

I have been looking online and have found many restaurants that give free dinners to children under a certain age, but I don't understand it.  Smaller children don't eat a whole lot and their meals do not cost as much as older children.  I would love to see restaurants offer discounted entrees for older children.

For example, if we go to a fast food restaurant it normally will cost us around $30.00, but if we were to go to a sit down restaurant it would be upwards of $60.00 easily.  I cannot justify that when we, as most families, are on a budget.  However, we would love to be able to enjoy a night out with all the kids, but it just isn't feasible in this economy.

I know everyone is not in the same predicament, although I just feel it's a bit of a disservice to those of us who do have larger families.  With this in mind does the restaurant industry realize there is more money to be made by offering a discount to teenagers rather than smaller children?  Teenagers eat larger portions which would in turn increase their net profit for lunches and/or dinner?  With all of this taking this into account it is quite possible more families would be willing to go out to eat more often then they do now.