usps strikes again

Show me the US law that states that postage paid is to a specific address.
I'll wait.
If you ship from Canada to the US, then you pay for the Canadian Postal Service to hand it off to the USPS. At that point it follows USPS rules. Same as vice versa.

That's the problem. There is no law that states that mail is to be delivered to a home address.
Trust me, the NALC has looked.
There is manual that outlines how mail will be delivered when there is an assigned delivery route, it outlines line of travel, and methods.
Your getting that notice is perfectly allowable. In fact they made those up, so no rule was broken. When I carried mail, I cut entire streets because of safety issues. One was a dog who's owners wouldn't confine, and the other was due to a crazy woman who threatened shot at us.
I live in Moscow Ohio, there is zero home delivery in the village.
We went to the P/O to establish home delivery because they close the lobby at 11:00 pm to 6:00am and completely on Sundays. We were denied. We took it all the way to our congressman and both senators. Nada!
You don't have to like it, but that's just the way it is.
In your case, I'd go talk to the neighbor who complained and see what their beef is. Let them know that their complaint has affected you and others on the road.
I'm also curious, is this a private road or public. If it's public, a neighbor can't do that, if it's private, they don't have to come down at all.

I work for the government. There are rules that dictate everything. I'm having a hard time believing that there isn't something written that dictates everything the USPS does.

That said, the interaction between my neighbor and the carrier (coincidentally the post master) was about speed. After a pissing contest, the neighbor said don't come down here anymore. Post Master said ok. Which is bullshit. I understand cutting off part of a route due to a safety reason. This is far from that.

You say they don't have to come down private roads, but every time I search that it says,
There also seems to be different rules for every area stemming from when that area was established and what services were requested at that time.