Possibly your original post should have been more specific, then. Or possibly you should not have generalized your experience without more thought.
We have two acres, and our electricity is generated by burning coal. We have a 16-hp John Deere lawn tractor. We live just outside of Ann Arbor, MI, about 5 miles away from my workplace. Hardly the boondocks, and only about $200,000 ten years ago. (Probably worth about the same today.)
Allow me to address your points individually:
Well, we don't use a trimmer, and relatively few of my neighbors (whose yards are typically one or two acres) do, either. I try to wait until
8 on a Saturday or 9 on a Sunday before mowing. (Mind you, I wake up at 4:30 on weekdays and no later than 5:30 on weekends.)So does electricity generation, except in those few places where hydro is feasible. Even that is not completely non-polluting if you take into account the pollution generated during the building of power plants.
Not everywhere. A pity I didn't open my electric bill last night; I might have more accurate info on electricity rates here. I believe it might be $0.20/kWh, but my memory isn't what it used to be.
Only if you fail to keep them properly maintained.
Only if you are irremediably disorganized. It's not difficult to keep the gas can filled.
Granted, if your lot is small enough. We had under 4000 sqft when I was a kid, and we had an electric mower.
For those rare occasions when I use a trimmer, I use an electric one, although it's hardly quiet. I'm only interested in trimming relatively near the house.
Cindy Hamilton