Where I live we have simple stickers that allow you to pick yes / no for receiving unaddressed mail and free periodicals. We simply slapped a no/no sticker on the mailbox and forgot about the junk mail problem but not every country has a system like that.
So what? So does food that is not eaten and other forms of waste. I don't follow sports but I understand that there is plenty of waste by people who drive to games, consume beer as well as other costs associated with sporting events. There are people who send out "junkmail" who are legitimate and get business from it. And they are selling things that people want. Obviously no marketing campaign is 100% effective (a few percentage points is usually good actually).
"If it was solely good then I highly doubt it would be called junkmail"
There are pros and cons to most things. Giving it a different name wouldn't make it better or worse. People also don't like television commercials or ads on web pages. If you asked them they would like to eliminate those as well expecting everything to be to their liking.
It's probably hypocritical of you to hate on junk mail while working in web development.