Hey @sifatsarker, thank you for your beautiful, lengthy comment! :)

You're right, we project the Earth's spherical surface on a 2D piece of paper and therefore convert (not always/ not necessarily) geographical coordinates into orthogonal coordinate systems in order to achieve preservation of the scale factor along given specific directions.

Thanks for mentioning all those Cartesian Coordinate Systems. The MGRS and the OSNG are used in very specific cases though.

Thanks for dropping by!