Data sharing plans deciphered (AT&T / Verizon edition)

GigaOm drills into the shared-data plans from AT&T / Verizon - which are, to put it mildly, entertainingly complex. 
First, to cut to the chase

...in general if you’re looking to connect more smartphones, AT&T comes out on top, but if maxing out data usage or connecting a lot of non-smartphone devices is important to you, Verizon’s plans fare better

Now that that is out of the way, what is it with the "used car salesman" approach to pricing?  I know, I know, snow the buyer with a ton of data, and work on the principle that if consumers overpay, its their fault because after all, they had all the data right? (Lets pretend that the logical conclusion of this - the financial crash of 2007 - never happened)
Still, here is the beginning of how the AT&T plan works

First, you need to select a data bucket. The following prices are for shared data between any number of devices either directly connected to the carriers network or tethered via Wi-Fi or cable. For instance if you buy a 6 GB bucket, all of your devices will draw from the monthly 6 GB pool. If you go over that allotment both carriers charge $15 for every additional gigabyte.

Now that you’ve got your data, select the number and types of devices you and your family will use. The reason for the different rates for smartphones, modems, tablets and feature phones is due to the fact that both AT&T and Verizon bundle in unlimited SMS and voice with each device. Feature phones make lots of phone calls and send lots of text messages while tablets do not. Why both carriers are discriminating between the all-data connectivity of a modem versus a tablet is beyond me, but they do.

Got that?
Neither did I, but who the heck cares - I'm sticking with my T-Mobile monthly plan and my $350 Nexus...