Splitting the bill evenly with CAOs

I was reading youngandthrity's and FabulouslyBroke about being generous to friends/family while not not receiving reciprocal treatment.  It was very obvious that there are people will are always willing to be treated and never offer to treat.  What about those that are not so obvious opportunists?  Like those who like to split the bill evenly when they have clearly ordered everything on the menu, and you have ordered one thing?

Mr LLF and I have some friends what we occasionally go out to dinner with.  Some are very gracious and generous.  Some I now see as Cheap Ass Opportunists.  We all make decent money.  Some are lawyers, some doctors(medical and otherwise) and some, like Mr LLF and I, are civil servants (read: not making money hand over fist, or will ever if we continue to work for the man). 

The CAOs will order appetizers to share, a drink, dinner, coffee, and dessert.  While the rest of us order dinner and a maybe drink.  I had actually sometimes ordered an appetizer as my dinner to save a few bucks back then. At the end of the night, when the bill came the CAOs will said "let's just split the bill up evenly".  Since it's usually a large group(7-10), everyone agrees out of shear simplicity, so that we don't have to sit and figure out who got what, and the waitstaff don't have to remember what amount on what credit card.  So at times our bill comes to $40 for a $15 dinner and $7 appetizer, when it would clearly be less than $30 with 10% tax and 20% tip included (which is way higher than what it really would be). This was back when we just finished school.  Now it's progressed to having beer/cocktails and a bottle of wine or 2 as well, and the group has grown with significant others(10-14).  I have stop trying to save a few bucks and order an actual dinner when I go out with these people.  But the bill is still $65 for $30 worth of food.  Okay, I will share the cost of the appetizer because we had a bite. but 2x the cost of the stuff we ordered?

We don't usually get a lot of the extras not because we are cheap or trying to save money.  It's that we know we will be full with just the entree.  Some times we will get dessert, most of the time not.   By we, I meant the non-CAO friends, not just Mr LLF and I.  I thought maybe the CAOs just assumed we all ordered as much as they did.  However, on another occasion I truely saw what was going on. 

It was a small group of people(6), and we had dinner.  I notice there were still the extras, just not as much.  And our bill came about to be just a little more than what we expected to pay, which was the cost of 2 dinners + t&t.  I was stunt at the fact the the CAO was able to control his spending for 1 night.  Or maybe he thought that in the smaller group setting it'll be more noticeable?

Do they think we don't see what they spend when it's a larger group?  Do they think just because they get stuff to share that we should share the bill so evenly.  I don't even think that half the people in the group want or eat the things the CAOs "share".  Is that the cost of a group setting, that we paid for stuff we don't want?  Since I am buying them drinks, will they ever buy me a dinner, other than the obligatory birthday dinner IF there is one.  Is asking for a separate check tacky?  Can you ask for them to put their drinks on a separate bill?  Can you say no when they want to split the check evenly, when everyone else agrees?

I think in the end, we only go out with the CAOs like 2-3 times a year and try to go to all-you-can-eat places like Maggiano's when we go out.  Even the all-you-can-eat places are starting to get rediculous because the extras.