A breaker bar is actually a non-ratcheting socket driver. Not something you fit over a wrench (for that you could use any chunk of pipe). Since a breaker bar (or actually the torque measuring version of it) is what is usually used to tighten such nuts I'd imagine it could be used to loosen them as well.
> Since a breaker bar (or actually the torque measuring version of it)
You're thinking of a torque wrench.
The pipe extension trick won't work for torque values far exceeding the rating of the breaker bar. I've snapped the head off a breaker bar with a pipe on it. Generally, I've needed a breaker bar with a 30% higher torque limit than the torque specs of a bolt/nut in order to loosen said fastener after it's settled (generally a few days). Change that to about 50% higher once the fastener has fused to its shaft/bolt/socket (months to years, depending on environment too).
If you could get a torque wrench for $5 that would torque down power line tower fasteners to spec, then yes, I'd agree that a $5 breaker bar would do the job. It should only be stronger than a torque wrench of similar price.
The thing is that the fasteners for power line towers are huge, way bigger than the fasteners I've encountered working on cars. Fasteners that large aren't practical to lay down with mechanical tools that amplify human strength. They'll require pneumatic or hydraulic power equipment.
I still agree with your basic premise that cheap equipment can easily destroy expensive setups with some creativity. Perhaps a fuel source like thermite or magnesium would work.
You're gonna need a breaker bar for that which will cost you more than $5 (but not much more... your point stands).