I learned about the 12% royalties for oil around 2000 when we were deciding whether to buy out my brother-in-law’s share of farm land in southern Illinois. As we drove around the countryside we saw a lot of the “grasshopper” type pumps along with a storage tank on people’s land. It seems the pump fills the storage tank and then someone comes by and empties the tank into a tank truck. Not much labor involved once the well is drilled. A lot of the rigs were pumping 4 to 20 barrels a day/week? I don’t remember now which. The farmers were not getting rich, but it was a nice, if small, steady income. We finally decided to sell, doing a Starker exchange for a piece of rural land much closer to home. The link below explains and shows some pumps in action. The ones I saw were mostly smaller than shown here.
https://en.wikipedia.org/wiki/Pumpjack
My g-pa used to lease the oil rights in seven year intervals, a trickle of income that helped him make ends meet (this showed up in the abstract of title). Based on the geology, anyone living over the oil-bearing strata has to agree to drilling, even if the drilling isn’t on their own property.