Welfare Ranching- A term coined by Western Watersheds Project and other anti-grazing on public lands "environmental" groups. I put environmental in quotes because if these groups realized the positive effects of proper grazing on public land they would be for it or wouldn't claim to be environmentalists.
Look at the statistics- 85% of the land in the western United States is unsuitable for crop production. By grazing livestock, the land area used for food production is more than doubled. Cattle convert forage that humans cannot consume into a nutrient dense food.
A California based study states cattle grazing plays an important role in maintaining the wetland habitat necessary for some endangered species.
Grazing reduces the amout of fine fuels on public and private lands helping to decrease the possibility of catastrophic wildfires. Why else would the USFS and BLM not allow cattle on permits the growing season before setting a prescribed burn.
Lastly, even though public land grazing fees are below that for private ground; there are many trade offs between the government and the permittee. On most private leases, the leasee doesn't have to maintain the fences. They don't have to build water sources. There isn't the extra bueracracy involved etc.