Clarification on monetizing complaints

There has been quite an interesting discussion in the comment stream of my earlier post about monetizing the complaint stream. I’ve found all the perspectives and comments quite interesting.
There is one thing multiple people have brought up that I don’t necessarily see as a problem. They assert that this idea will only work if all ESPs do it because customers can just say, “Well, Other ESP will let us do this and not charge us.”  I don’t quite understand why this is an issue. Customers already do this.  In fact, sometimes the assertion is actually true.
There are ESPs that let customers spam. There will always be ESPs that let customers spam. This is not new. Changing a pricing model isn’t going to change this.
As I was envisioning the monetization process, ESPs who wanted to do this could actually offer multiple tier pricing. The customer can choose a lower price point for their overall mail program, while assuming the cost of their recipients complaining. Or the customer can choose a higher price point and let the ESP absorb the cost of handling complaints. In either case, the customer would still have to meet the ESP’s standards for complaints and comply with their TOS.
Clearly I’m seeing the idea and industry differently than a lot of my readers. I’m interested to hear the thought process behind this so I can better understand the objection.