Many persons transfer the bulk of their assets to their beneficiaries before death. I don't believe it's a privacy issue rather than a sense issue.
Many wills are smaller than one may have thought for a number of reasons. The write down of asset values is one thing that springs to mind. Second, there are Trusts which have been set up which fall outside the CAT category. Finally for those that are nosey, maybe people don't leave as much as what was thought as they simply may not have had it. An enjoyable and good life costs money, a lot of money.