I use rechargeable batteries and intelligent chargers almost everyday and the capacity stated by the manufacturers are generally quite accurate depending how you treat the cell. Dry cell manufacturers however have been getting away with murder since they only have to describe the physical size i.e AA A B,C,D etc and a voltage but no capacity apart from heavy duty ! , have you ever seen a light duty battery sold ? ! No.

It would be akin to buying a gallon of 4 star petrol but you don't know how much is in the can. It can't be beyond them to state a capacity on an "urban cycle" just like an MPG for cars.