Can a girls heel crush a toe?

Sure

But it depends on how thick the heel is and what the weight of the girl is.

The thinner the heel, the easier is will be to crush a toe.

But I think in most cases, if the person whose toe is being stepped by a heel is wearing shoes, it will not happen by accident. But if she really wants to crush some toes and she jumps and lands with all her weight on her heels on someones toes, the will be crushed.