Why do taxpayers have to subsidize junk mail?

Funny you pose this question. In large, moderate Western state a couple of years ago a state representative actually proposed banning junk mail. Businesses and postal workers came out of the woodwork to make sure junk mail continued to be delivered to that state's residents. Government at work; if you can hire a lobbyist or PAC, you interests get defended and/or promoted. The other 95% of us get stuck with whatever laws the legislatures come up with.