USPS will always deliver mail, but you can refuse to accept it. If your mail carrier doesn't follow procedure, then... ¯\_(ツ)_/¯

https://faq.usps.com/s/article/Refuse-unwanted-mail-and-remo...

I agree with your other points. Stop the subsidies. I'm not sure why spam makes me so irrationally angry, but it does.