I have used Round-up or equivalent for ages and find it to be easy to use, effective and not harmful to surrounding plants ... unless you directly get it on them. Some people are careless in spraying, have not very precise equipment, or ignore the fact that there might be wind. All those things can cause Round-Up to land where it is not supposed to. Spraying for weeds in the cracks of driveways requires a lot less care than spraying weeds in a planted bed (which I have done many times without problems, but I also use a very precise fan spray tip and don't do it on windy days.)

Many people do not understand how Round-Up works. It must be sprayed on the FOLIAGE AND GREEN STEMS of plants in order to be absorbed into the plant's system. Spraying it on the woody bark of a plant or on the ground around a plant will not be effective because it will not be absorbed by the plant. Different plants have different resistances to Round-Up. There are some plants that are NOT AFFECTED AT ALL by it. They cannot be hurt or killed even if sprayed repeatedly. However, most plants are going to suffer some degree of harm and many plants will die from one application of Round-Up. (That's the goal!) Only experience will tell one how a plant is going to be affected by RU so the newcomer has to behave as if all will be affected.

IF a plant is able to be killed by Round-Up, it still cannot be killed unless a certain amount of it gets into the plant's system. If a plant requires 50% coverage of a certain strength of RU in order to die, and you only get 10% on it, it's going to be injured, look sickly or maybe have dead parts, but later recover and move on. Lots of times, RU kills the plant top and the plant comes back from the strength left in it's roots.

Round-Up also breaks down rather quickly in the environment. What was sprayed on a bed a week or two earlier will not have enough power left in it to cause damage even when foliage comes in contact with it. When preparing a new bed that is presently grass, it has been the standard practice for years to wait one week before planting, after spraying with Round-Up.

I'm not saying to be careless with Round-Up. But don't think that it is going to be like an atomic bomb and wipe out the county. It just doesn't work like that.

I might hand pull a thistle or two out of a planting bed but there is no way in the world I woud bother hand pulling weeds out of a gravel driveway!! This is one of the best uses for RoundUp and an easy and efficient approach. Just do it on a day that has minimal to no breeze to reduce any chance of the spray mist drifiting on the breeze to another area.

Canadian Thistle will have multiple plants on the same root system, so be prepared to have to keep at them for a while. I did have to resort to RU to finally eliminate them.

Trouble with blow torch is that any perennial weed is going to come right back from the roots. It's a temporary control, not a solution for long term weed eradication (which will take more than RU, too.)

^^ Same with the vinegar. Both the torch and the vinegar can burn off the top growth but neither has any impact on the root system of any perennial weed.

There is a very good reason why RoundUp/glyphosate is so wdely used. It does what it is supposed to do very effectively and efficiently.

After you’ve killed the first round, I’d see if there’s a granular or liquid preemergent that would keep the weeds down for the season in the driveway.

Sure, vinegar would work IF you can douse a root system, but that's not practical for most weed removal (nor safe for adjacent plants if there are any).

Oh my, I remember the day when I moved into my new rental. Both the front and the backyard were full of weeds, and I also noticed that there were a lot of squirrels among these weeds. They were so annoying! I always pull the weeds by hand. I think this is the most reliable way to get rid of them. But, to get rid of the squirrels I needed help. I called the guys from wildlife removal and they took care of them immediately. Now I even have my own small garden, with lots of fresh veggies, which are always a better choice than the ones from the market.