Tallow, back in the day, was really cheap. It was used almost everywhere to cook with and the cattle industry was partially built around supplying it. The seed oils they replaced it with are only cheap because the government heavily subsidizes those crops (gee, I wonder why). You can still find lots of cooking tallow around. It's more expensive today because of inflation, and that it's been so thoroughly demonized by mainstream "culture" and "science" that it's become more of a specialty item, reducing supply. While beef fat is still used in other industries, a lot of it is thrown away after a cow is butchered, which could otherwise be used to produce more tallow and reduce prices, if not for the unfair demonization of it.