Good point. However, in areas where the weedeater is useless and chemicals are out of the question (like around the fence line of my chicken pen) then $2/gal for vinegar that has to be re-applied once a month is a do-able deal.
A torch may kill roots of some tender vegetation or very young plants. It will not kill roots of many grasses or broadleaf weeds with an established root systems.
If you use a torch to kill grass and weed tops in a gravel parking area you are left with a black residue that people track into your house on arrival or into their car when they leave. And it does not take long for the grasses and many weeds to re-sprout from the roots.
In my gravel parking area and my gravel driveway I tried a torch, I tried pouring the white vinegar (is that 5% or 6%, I can't remember). I poured it to try to kill roots instead of spraying it. I now use Round-up.
My BFF1 uses her water softener salt to kill the grass on her driveway. Since the drive isn't used for anything else, I don't figure there would be much of a problem. Just sprinkle along the grassy/weedy area and let set. Unfortunately her driveway is a lot longer than her year's supply of used salt can cover so she doesn't get every thing done until every three years. Big difference though.
It is a salt, however, and can't be used just anywhere. On the driveway it is more a case of one chemical or another.
Gypsy joke: Did you hear about the girl who was hit with a block of NaCl that fell from a truck?
Sorry, no before pictures, but here are two to start with. I'll take more later. My job isn't finished, just YET! This is the Brush Hog that I rented. It was $80.00/day, and I got it for two days, $0/2nd day because they are closed on Sundays. I also paid a $12.00, non refundable damage fee. The machine sells for $2,200.00, so I thought that was worth it. I think we ran it about 12 hours total. The 2nd picture is the first fence line where DD's and went back and sawed any burdock, thistles or saplings that we had missed. (It was the first fenceline that we bushhogged, and we got better at chopping everything as we went along.) We sprayed vegetation killer about 12 inches on both sides under the fencing and they covered it with used stall shavings and debris. We're kind of in a summertime drought right now, so THAT will help, too.
That's a lot of work done. Machines are THE way to go when working if possible. They make work easier and keep me motivated to continue working so as to get as much use as possible from the machine before returning it.