Apparently, Verizon didn't originally list the full breakdown of Shared Data Plans (aka the "Share Everything Plans"). They actually have some higher tier plans that they don't advertise at all. The only way to get them is to ask for them. Here's the skinny in a quote,
It seems a mystery as to why they wouldn't have included these before, but who knows... Also, according to the source of this article, Verizon recently put this info up on their website, although it is still not obvious because I couldn't find it using a quick scan search.[Verizon] has five additional unpublicized tiers available for Share Everything users: 12GB for $110 a month, 14GB for $120 a month, 16GB for $130 a month, 18GB for $140 a month and 20GB for $150 a month. As with the lower six tiers, each device added to the plans will cost an additional $10 per tablet, $20 per Jetpack/USB dongle/notebook, $30 per basic phone or $40 per smartphone each month.