Carbon Forks, how fragile?

Even if you carve your forks out of T-Rex teeth, stolen from the local museum. As soon as you crash them they will need replacing.

One of the worse failiures I've ever experianced, was with some previously crashed steel forks.

Carbons weakness is clamping torque. Focused torsion can make it fail.
Steels weakness is rust. Hidden rust can make it fail.
Alu weakness is fatigue. Over time it can crack and then fail.

Shit breaks.

Yep, but the drawback of carbon is that very often you can't see any surface damage. With steel and aluminium you can see creases, rust, damage to the welds... Also, steel usually bends before it snaps, giving you at least some warning.

My fear is crabon fork users who may have a 'slight' accident (crash into a kerb, low-speed car door etc) and decide that the fork 'looks okay' may then hit a pothole at some point in the future and their fork explodes on them.

'Commuter friendly' bikes below £500-600 routinely come with crabon forks these days, and I reckon 90% of their users don't know about the need to replace crabon bits post-crash, even if they look fine.