If you've ever braked hard, you've used ABS. Its what let's you continue to steer under heavy braking. Previous generations were taught to pump the breaks for a similar (much less effective) effect.
The fact that you've used it and don't know it proves your point. That's an example of good safety implementation.
I have never needed to brake hard enough for ABS to kick in, or at least not intentionally - I don't count wellying on it hard to seat new brake pads, for instance, nor do I count traction control coming in (which uses ABS) under load on loose slippy surfaces.
It's easy to tell when it does - it makes the same BRRRRRP noise it does during the ECU's startup self test from the valve block in the engine bay.
Why do you think smart cruise control is useful?
I can't tell if ABS is useful or not. My car has it but I've never used it.