There's elements of both censoring and causal inference here. For a given customer/checkout: if they buy you know the demand was higher than what was displayed. If they don't buy, you know it was lower. But exact demand is censored. The causal inference aspect comes in since you can only display one set of options at checkout time so the demand in the counterfactual case (if you showed the customer a different set of display options) is completely unknowable.