People who earn a living clearing weeds will likely spot spray. Boiling
water probably won't kill a lot of established weeds. Maybe concentrated
vinegar which is still pretty nasty stuff. For home gardening I've
tried lots of other methods by hand, long screwdriver, mowing etc.
Something like this works well for all kinds of weeds at the cotyledon
stage, past that you might just be wasting fuel.

On the topic of boiling water is steam distillation. While volatile organic solvents are quite powerful, water itself with heat is an excellent clean solvent and has a high heat capacity.

Boiling water, poured on a plant, will kill the top growth but probably not much of the root. To clear some weeds with boiling water would require several repeat applications while others may be wiped out the first time.

If you have some of those "weeds" actively growing now take care of them. Many of the winter "weeds" will be producing seeds soon.

Thanks for the responses! I guess the long story short is that there is no quick, easy way. I may try the boiling water on the matricaria just because what do I have to lose? The brambles, I'll have to start by taking the electric hedge trimmer to them. Sigh.

I've done the same as spedigrees on my public sidewals, but it's fairly labor intensive for a large area.

Useless on brambles and other woody plants.