Back in the 1930s, shortly after prohibition was repealed, the States wanted to set up systems to control and tax alcohol. They successfully convinced the federal government to leave it all up to the States, so each state began to set up its own system. Most of them rely on a system whereby no one company can make the liquor, distribute it to stores/bars, and also sell it to the public. They split it up so that one company could brew it, and they had to pass it along to an independent company for distribution and then the distributors could deliver it to bars/stores who could then legally sell it to the public. This prevented alcohol monopolies and allowed the states to track and tax the alcohol at 3 different steps. Monopolies had been common before Prohibition. Beer companies would brew the beer and ship it to the bars they owned all over the region. It was easy for them to adjust the books so that it looked like they were making and selling less beer than they really were and, therefore, avoid paying some of the taxes.
For that reason, most states set up the current system whereby the brewer, the distributor, and the retail outlet could all be owned, licensed, and taxed separately. An unfortunate consequence of this is that the price got raised at each step as well.
In some states this presents a problem for brewpubs and micro-breweries who want to brew and sell directly to the public, cutting out the distributor middlemen. In some states that is still illegal, and in most states it’s a bigger problem when the micro-brewery wants to grow beyond a certain size. If a micro-brewer needs a distributor to sell 50 barrels of beer a year, the distributor has little incentive to bother with them. There’s just not enough profit for them to care about, much less promote the micro-brewer.
All that notwithstanding, distributors have had close to a century to build their political and financial strength. Many distributors have become vastly wealthy and incredibly powerful in their regions. They collectively donate millions of dollars to political campaigns and lobbyists, all in order to perpetuate their incredibly lucrative businesses.
Distributors are the guys who really control the beer/alcohol system. If you want to open a bar or liquor store, you must get your alcohol from one or more distributors. If they don’t like you or decide you aren’t worthy, they can refuse to do business with you, and you’re dead in the water. If you don’t pay them, they stop distributing to you, and you’re out of business. Most states make it illegal for a bar owner to simply go to the liquor store to buy alcohol and resell it to the customers at their bar.
Since the 1930s they have been building political clout, and can likely call up the governor and other state political elites in order to block or create new legislation as they see fit. On the state level, these guys have the most political clout. These are the guys who control the Beer Conspiracy in your neighborhood.
Need more proof: Grab a cold one and sit down with your internet-connected device and google the heck out of it. You’ll see!