A Frenchman by the name of Roberval made a very significant contribution to balance technology when he devised a balance structure that would not only eliminate the undesirable effects of off center loads but also allow for balances to become top loading, thereby eliminating the hanging pans. These balances existed side by side with scales for many years.
The term “scale” has many meanings in different applications. Most maps show a scale on them which relates the distance between points on the map to the actual distances that they represent. Models of physical things are similarly scaled. Automobiles have speedometers where a pointer moves over a scale that converts pointer position to velocity. A ruler is a scale used to accurately measure distances.
In weighing the term “scale” has come to mean an apparatus which converts the weight of an unknown into a directly readable value by means of a readout which is scaled to weight values. Think of the fisherman’s spring scale where the scale is hung from a finger and the fish is hung on a hook or a pan, and its weight stretches a spring which has a pointer that moves against a scale that has weight calibrations on it. Think of the grocers spring scale with its round dial that is used to weigh produce. Think of the older bathroom scales that were mechanical and provided a circular or linear analog readout.
The modern laboratory and analytical weighing devices which use magnetic force motors as their sensing elements (these are the high accuracy devices used by science and industry) are hybrid in the sense that they use a force servo to balance out the unknown weight, and then they measure the current value required to balance the unknown weight, and then they scale it to produce a direct readout of the unknown weight. The Roberval structure is preserved thru the use of flexures which eliminate the side loading effects, but the equal arm concept is no longer required as the restorative force is applied directly to the pan with the unknown weight. We are all correct.
The industrial weighing devices which incorporate the strain gauge as their sensing element are truly scales since they use electrical sensors to measure the deflection caused by the unknown weight upon a mechanical structure (usually some sort of a cantilever). These devices should always be (and usually are) referred to as scales.