For calculation – Avoirdupois / international pound equal to integers 0 and fraction digits 4 5 3 5 9 2 3 7 kilogram. Avoirdupois pound is widely used in English speaking countries.
For some countries – English is the default language.
Fast in use – do not need connection to the Internet.
For simplicity – only whole numbers and rounding.
Simple and fast in use when you need to convert a unit of weight, from kilogram to pound or from pound to kilogram, with a simple graphical user interface.
Also for tablets.
(note: pound = LiBra = lb or lbs)