The USPS claims that bulk mail more than pays its way. In fact, there's a federal law requiring that.
Yes, bulk mail does pay a lower rate. However, it must obey certain constraints which the USPS claims result in significantly lower costs. In other words, bulk mail is supposedly profitable even though they charge less for it.
If you're going to argue that they screwed up the accounting, you should show your work.
Why should we enact your preferences instead of, say, mine?
Note that it's quite possible that spam is helping to keep first class postage prices down. (Eliminating 30% of the USPS's revenue does not eliminate 30% of their costs. FWIW, I suspect that direct mail is a greater percentage of their revenue than 30%.)
While you may willing to pay more to send USPS mail in return for getting less spam, other people probably aren't.
Which reminds me - you have gone to the very slight trouble of the first two steps listed at http://www.epa.gov/region1/communities/stop_spam.html , right?
The problem is that the post office exists mostly because most rural mail costs more to deliver than the price. It is in the government's interest to make sure that it can send and receive mail to and from all pieces of the country (for taxes, the census, and for general commerce for rural areas. )
As such, bulk mail is a subsidy.
