Cost to dispose of it is greater than zero.

I was looking for a comment mentioning this. If it’s a rural area, the local waste management facility might take a trek to get to. If you have to make multiple trips, or rent/hire a vehicle to get rid of something (like having to tow an old car), the time and cost can add up.

So if it’s not accepted with a typical trash pick-up, it’s still gotta be somewhere, even if you don’t want it anymore. Keeping it on your own property is at least more ethical than dumping it in the woods somewhere (though you’ll find plenty of that in some areas, too.)