Yes that is a good point...One thing I liked about the Volt bikes was that you could actually vary the way the assistance came in and set you own power levels.It's worse with ebikes because the range is affected by how hard you pedal. Some systems force you to pedal hard, so that the proportion of power that you provide is higher. Not surprisingly, they tend to go further than ones where you can take a rest and let the bike do the work.
I did find it funny actually looking at the looking at the number of bikes that have the Bafang 8FUN 250W motor and very similar batteries seemed to do very dissimilar distances...and yes I know this depends on the rider, the way the controller is setup, etc etc but it shows the complexity of what should be comparing what should be apples with apples.