(US resident). I haven't gotten one piece of junk mail in nearly 15 years (except for a few generics addressed to "resident", but even they are uncommon). Before that it was weekly shiny newspaper type ads and letter spam by the pound with a tiny bit of real mail.
It was an accident but here is how I did it.
I had a temporary job back in early 2000's so I got a short term lease in a different city and opened a PO box at post office. Then I unexpectedly got called back and was slated to return but didn't and neglected to close the PO box and forward mail. I was a road warrior for next 5 or 6 years and seldom at permanent address, so I didn't bother putting in address change back to permanent residence. Instead I got an online mail service (I don't know if was this, but something like this https://www.postscanmail.com/) that opened and scanned mail and I'd read it in browser, download scans, and have important stuff physically forwarded to wherever I was at the time.
Finally that all ended and I got a real address and stopped the online mail receiving. For whatever reason something in that process completely stopped the junk mail to this day and it's wonderful.