With respect to refineries, the oil companies are obviously able to supply us 99% of the time with the product we need. Therefore, they really don't need more refineries, and that would be a wasted capital investment. It might be "interesting" if there were refineries in all large cities, or based upon population distribution, but I don't think we should be blaming the government for this. I don't doubt for a second that the government would make it very difficult, but, like I said, we're not struggling with fuel delivery.
Customers are always at the mercy of an industry. As for the fossil fuel market, it's even less monolithic if you look at the big picture. There is natural gas, LPG, diesel, coal, and so forth. It's not just gasoline. And yes, there isn't much competition to the fossil fuel market, but that speaks to the success of fossil fuels. There isn't much competition to the food market, either, but that's because I can only eat food.
Unfortunately, yes, there are needs at times for $100 plus oil and more expensive gasoline. The world may be awash in oil as you say. But, shortages or even supply hiccups aren't just based upon how much oil is in the world. If Saudi Arabia shuts down their wells, prices will go up. They're awash with oil, too, but if we can't access it, it might as well not be there. And yes, there are plenty of other suppliers, but they're not online, with a man waiting at the faucet, either, ready to fill a tanker.
Look at what happens to diesel every year up here. In the winter, the price goes up because of home heating demand. In the summer, it drops way back down because of the lack of home heating demand.