This is something "everybody knows", that it is "heavily subsidized" but I'm not aware of what rules and regulations are written to favor and apply only to the industry. Maybe you could summarize a bit?
The easiest to spot is the favorable tax treatment. The oil industry has a sweet deal that slashes taxes on oil investment. The provisions are complex and written to facilitate big investments in this industry [1].
1: https://www.energyfunders.com/blog/oil-investing-benefits/