> I guess they were just wasting their time with
> these vehicles then...
Not at all. Those escape systems sat of top of liquid
boosters, which could be shut down to allow the escape
system to get away.
An exploding liquid booster cannot be "shut down." Those towers were designed to get the capsule away from the stack in the event of a catastrophic booster failure. yes, there was a finite chance that the vehicle would not get away quickly enough, but factor in directional changes and it gave the crew a chance, more than they have now with STS.
Only the second and third stages of the Saturn stack could be powered down. When the S-1 was lit, you were committed to see it through. The Atlas booster used for Mercury also had no shut-off switch.