That's exactly what happens. But all that software points to pre-existing data, and that data is manually entered, usually by some grunt. In this case, the grids are a set of hand-digitized polygons hand-numbered at a keyboard by someone like me and thee. The numbers are fields in a tabular database, containing numerous other fields of different data items, their corners are coordinate pairs, the GIS does the easy stuff, after the data is designed, created and assembled into the right format. The GIS software is commercially purchased, and the application is coded up, but the relational databases are made by hand by people staring at maps or aerial photos..

This all starts off as analogue data, and somewhere up the line, someone had to actually point, click, and type.