Another reason they don’t build additional capacity is they are banking on the notion that when public outcry gets loud enough, the government will pay for the exansion, rather than the oil companies paying for it themselves.
If the Government changes regulations so often that retrofits are not implemented before they boecome obsolete and then threatens fines of six figures or more a day, you shut down.
We used to have a small refinery near where I live. It was dismantled and shipped to someplace in Africa decades ago, not because it was incapable of producing fuels, but because the upgrades, new environmental compliances, and other regulations involved would cost more than the projected output for the life of the refinery.
About half of American refineries have met similar fates in the last three decades, all at the hands of Government regulation, NIMBYs, and the dirt worshipper lobby.
Nope. The Government is not doing the industry any favors, at least as far as permitting any refinery construction goes, and while that may seem like a good deal for the oil companies, it sticks them with maintaining and upgrading existing facillities and losing revenue during the downtime.
The traditional means of growing involves capturing market share, and the ability to out produce your competition can put you on that growth curve.
Waiting until public outcry "gets loud enough", in the current political climate, would be more likely to lead to government takeover. If you think fuel is expensive now, wait until you have to get it from scalpers on the black market.