Mainly because many manufacturers no longer publish much of this data. ILD, Density, and Hardness are no longer published as they once were. This may largely be due to the number of different types of foam available today, where these measurements are not longer as comparative between types of foam as they were (e/g/ latex vs. memory foam vs. gel memory foam, etc). We could contact manufacturers, but many businesses do not manufacture the mattresses they market. It would not be a fair comparison to publish some manufacturers’ data but not all.