Why are some businesses capital efficient?
In general there tend to be two drivers of capital efficiency.

Customers will pay (a lot) for the product. The “capital” side of capital efficiency is often a proxy for both product / market fit and an intense customer need. Customers are willing to pay up for a product that is important to them, and there is insufficient competition in the market to commoditize pricing or destroy the category (so the product is somehow differentiated). Pricing is often a proxy for value & differentiation of a product.