V1, of course, is the certified speed for which you have limitations. There's no certification basis of 80 or 100. I seem to recall a line about it in the AI FCOM or FCTM that, for the purposes of RTO, 100 kts is a arbitrary figure.
The A300-B2's airspeed indicator is missing the 80 mark, so it seems Airbus came up with 100 kts 40 years ago.