Out here in the boonies, this is still commonly done.
The alternative is to have the vet come to the house and administer a shot. This is also common, since large animal vets do travel, and in the boonies you are usually talking cows and horses.
I had the vet come to my house to put down my suffering old pets also. I agree that taking a suffering animal to the vet is torturous for the poor guys, home is so much better, vet or no vet.
There is a major problem here with a recent law that prohibits people from burying their horses on their property. It has resulted in the very inhumane practice of turning very ill and fragile animals out into the wilderness to die, so the disposal of the bodies doesn’t bancrupt the owners. It is expensive, and many country folk just can’t afford it.
Some of these laws may be well intentioned, but they do cause unneccessary suffering.