Everyone has different needs, different existing environments, different service expectations+++
So you can't effectively stick to one price for the "large" tier. Given the differences in complexity and capacity consultants are needed. Startups can't build in-house service teams - the economics are misaligned. Not that you can get away from consultants if you buy from Salesforce, Oracle, SAP, or IBM...
Plus there are issues in terms of pricing and domain expertise across different industries - Federal, Education, Health.. legal issues in what your pricing can be and serious issues around their compliance environment means you need different teams of people to serve different verticals.
If you really need HA you are going to call anyways to negotiate. No one puts 15000 licenses on a credit card.