[glabifrons]

They've raised the postal rates for first-class mail (that normal humans all use) many, many times. Not a complaint, just an observation.

Why not raise the rates for junk-mail?

Sure, megacorps will scream and cry that it'll put them out of business, but it won't. They'll continue sending out junk-mail as it draws in far more in customers than they spend on it. If some don't, that much better for the environment, since I'd guess >99% of junk-mail goes straight into the garbage (with a small percentage of that being recycled).

Seeing as the vast majority of mail I've received over the decades has been junk-mail, it should be an easy way to increase revenue.