How about the following scales? Are they also an issue?

 - Time (Calendar) relative to either anno domini or Unix time?
 - Position Coordinate relative to Greenwich?
 - Electric Potential relative to earth potential?
 - pH, pKa, pKb scales relative to a neutrality of 7?
 - Decibels, phon and sone relative to threshold of human hearing?
 - Pressure (hydraulic or blood) relative to atmospheric pressure?
 - Altitude relative to sea level?

   -> For pressure and altitude there are lots of other scales, e.g. used in aviation
 - Richter scale relative to detectable earthquakes?
 - Beaufort relative to calm wind instead of zero wind?
 - Borg physical exertion not starting at zero?