OK, on my property, which is definitely not "rural electrification," I am subject to this single-wire earth return.

One thing I note, if I place voltmeter probes in the dirt of my yard twenty or thirty feet apart and in parallel with the power wires on the street, I see a significant voltage on the voltmeter. Single digit voltage.

Can I take advantage of that earth return? Maybe to charge batteries?

@#3 ... s that actually earth return and not induction from the overhead line? ...

I do not see a "return line" on the poles here. Just the "feed line."

So, yeah, I'd say, it is earth return.

Stated differently, I see the transformers being fed from the wire on the pole, but I also see a line from the transformer down the pole into the ground. Combined with the lack of a return feed, classic earth return configuration.