As far as the prices being different on different brands of beer I would agree that is ludicrous. It may possibly be related to alcohol content.
Being a recent graduate of OSU I have certainly been in more than one situation where the minimum price on beer in Ohio affected the volume of my consumption of beer. I have been involved in more than one situation where the price of the beer regulated how much we bought for an event. If I had been able to get beer for half as much I almost certainly would have bought twice as much on many occasions, and been twice as friendly to anyone I did not know who showed up. We simply had a budget and maximized the alcohol we could get for that budget. I would guess very few of us could claim that raising the price of beer by 100% would not affect our consumption.