Consumer telecom is simple because providers have chosen to simplify the pricing strategy, not because they don't have other billing metrics available. You aren't required to have a complicated pricing structure even for incredibly complicated services. Doing so is a deliberate product choice with consequences.

They're also not truly fungible, though that's mostly for the higher end of the consumer market. Think about TMobile's "uncarrier" marketing, or Verizon's network coverage marketing.