I disagree. I think in a lot of cases buyers should or would demand transparency (ie. has this house ever been flooded?), but I don't think it's a strict requirement in the broad sense you may be implying.
Transparency can be subjective. For example, a person sells 100 shares of ACME stock to a savvy buyer. A short time later the stock triples in value, and the seller sues the buyer because they were not "completely transparent" about their knowledge that the stock would rise.
Of course, in all of this I am not talking about deliberate fraud which would be strictly forbidden in a free market.
Transparency can be subjective. For example, a person sells 100 shares of ACME stock to a savvy buyer. A short time later the stock triples in value, and the seller sues the buyer because they were not "completely transparent" about their knowledge that the stock would rise.
Of course, in all of this I am not talking about deliberate fraud which would be strictly forbidden in a free market.