Junk mail is bad. But voters going around thinking that taxpayers are funding junk mail is much worse. If large fractions of the citizenry can’t apply common sense and develop a working mental model of how the world works, we’re all dead. And I don’t mean that figuratively.
In 2011, most of what the USPS delivered was junk mail[0] and it's only gotten worse[1]. Junk mailers pay less per item than first-class mailers (actual mail). The USPS operates at a multi-billion dollar loss every year. Intuitively, we're subsidizing junk mail.
If you get lots of important items 6 days a week via first-class mail then I can see you having the perspective of junk mail is actually subsidizing this important service.
However, my guess is that most people don't. This is based on my own lived personal experiences and those of the extended network of people in my social circle. It's not made in a vacuum. Therefore common sense is that we're subsidizing an errand of cleaning trash out of our mailboxes several times a week.
I get that people are sensitive to government services under the current political climate but there is no reason we couldn't cut back service to say 5 days a week instead of 6.
This is not intuitive. We're maintaining a service because we have made a democratic decision to provide that service. The junk mail is subsidizing that service. I hate junk mail too, but we don't get to claim that the sky is "down" just because we're standing on our heads.
We could make a decision to cut back service if we want, but we haven't. I strongly suspect that part of the reason we haven't decided to cut back the postal service is that many voters are elderly and find the postal service vastly more essential than young technical people on HN do. I'm not in a position to tell society that it's wrong.
(And frankly, given that we barely have a working electronic payment infrastructure in this country that can serve that audience, I'm not sure we're ready to do that.)
Junk mail is bad.
Full stop.