The LDS Church has records that are donated to it by its members and others. It also has an extraordinary collection of microfilmed church records from little churches (of all denominations) from around the globe. These churches are often very sensitive about their records and how they will be used. These records are made available free to any individual who wants to do genealogical research through an LDS Family History Center, but they are NOT made available to commercial organizations such as Ancestry.com.
Ancestry.com, on the other hand, photographs public records such as census documents or licenses private records such as shipping manifests, indexes them, and sells access to the indexes and photos. They are free to resell their data and, by selling the company, that's what they'll be doing. They own the copyrights of the hi-rez photos of old census docs, even though the docs themselves are in the public domain.
Ancestry.com, on the other hand, photographs public records such as census documents or licenses private records such as shipping manifests, indexes them, and sells access to the indexes and photos. They are free to resell their data and, by selling the company, that's what they'll be doing. They own the copyrights of the hi-rez photos of old census docs, even though the docs themselves are in the public domain.