Exactly. My oldest daughter went to Pre-K prior to starting kindergarten at the parochial school she attends. It was not mandatory but since kindergarten at that school is full days, 5 days a week the Pre-K program is designed to better acclimate them to that just as a public Pre-K program is going to ready (with any luck) the children for whatever public kindergarten requires of them.
Personally, if it weren't for the full day scheduling I would have never even sent her to Pre-K, though.
If your main concern was acclimation to a full day schedule, there is no reason why a private pre-k couldn't accomplish this goal as well or better than a public one, even if the child will be going to a public kindergarten.
The point here is the bias of the reporter in calling public classes "pre-k", and private classes "day care". There are many fine pre-schools in the private sector, and they should be recognized as such in the press; that is, if they strive to be fair and balanced. :)