I think that South Carolina is the only State left that still uses mini bottles. I think that the state gets 50 cents a bottle in taxes so it is easy for them to keep track of what income they should receive. It is also far more in taxes than they would receive if drinks were poured from regular bottles. . Of course there are lots of drinks that we can not get down here , as you might have to open several bottles for a drink, and end up with 6 oz. of booze and a 15.00 drink. Also the selection is very poor, and usually all you can find is the Beam line and Makers Mark.
While obviously all of this is bad for the consumer,many restaurants like the minis. They have few inventory problems,and it is easy to keep track or 'shrinkage'. Also you don't need to hire talented bar people, and you can stock your whole bar in an area not much bigger than a suitcase