Actually, that's debatable. First, most 80 columns cards had the last 8 columns ignored (or used for metadata). Second, it is much more probable that 80 columns limit comes from 80x25 text resolution of EGA/VGA displays.
There were multiple punch card sizes and formats; some were as small as 45 and some as large as 96 columns. Eighty does seem to be the one everyone remembers.
Neat. I had always wondered about this.