No more theft than putting a solar panel under a street light that's shining on your property.
This is equivilant to throwing an extra belt over the shift to power your own machine.
There's only so much power available and as more and more machines are driven there's less and less ommph to power more.
This is literally adding "drag" to the overhead power line and decreasing what reaches the end point of transmission.
It's not equivilant to scooping up photons that were being thrown on the ground anyway.
Your analogy would be better if it were asking if it’s okay to walk through the store daily and take a couple grapes to add to my fruit basket at home.
Enforcement and legality are separate things. Many people break the law under the assumption they will not be prosecuted. They're still breaking the law.
That's OK. But it's worth knowing because eventually enough of those small choices add up to something that does trigger the laws attention.
There's another reason this behavior might elicit enforcement: in many cases, failure to enforce property rights can become grounds for losing rights or being unable to enforce them in other contexts. So a large company may have an incentive to go after someone like this just to make sure that other people don't start doing more ambitious versions of this.
So much for all your supposed "justifications" for doing so. Have you completely lost all sense of proportionality here? Or has the legal system gone completely bonkers, then? Or are you trying to gaslight me?
We're talking about 0.1 watts of electricity being "stolen" at most.