I'm pleased you make that distinction, perhaps when stating your bike will do 100+ miles you could also say that some owners may only get 30 miles.there is no reason for me to argue with your personal experience. I sell bikes to people of all shapes and sizes, each customer has his/her own requirements, there isn't one size fits all solution. As I said, here is the tool to guesstimate what battery capacity you'd need. You can input your weight, bike's weight, frame type, wheel size, tyre type, wind speed, elevation etc. Change the power input to get to your target speed then subtract that required power by how much you want to pedal, then you'll know what battery you need.
I'd hate for someone to buy a bike that the retailer claims will cover 100 miles, only to discover it will actually only do 30 miles in the terrain they cycle in.