"The 100 knot call out reminds you that you are now in the high speed regime for aborts. Thus limiting aborts to fire/failure, unsafe to fly..."

And why do you think the manufacturers built in all those auto features like sound inhibits except for the most critical?

"757 767 and 777 the autobrakes apply on abort above 85 knots not 80 knots. I thought the 80 knots thrust set was due to a/t to hold"

Again. no kidding, is this a PC or something? If you want to get technical, which ones are airspeed and which are GS? Come on now by the time the 80 knot call is made (some time after 80 knots) the thrust will be in hold and the rest of the auto functions will be engaged.

The reasoning behind the 80 knot call is because the thrust will go into hold and if the pilots were slow at advancing the throttles they will not have the correct takeoff power. Additionally it is where officially the high speed regime actually starts (according to how the manufacturers designed the system) so aborting above that speed needs to be taken seriously.

And for info UAL is adopting the 100 knot call because of CAL.