VFR in CAS D is under a Radar Control Service.
Not strictly true. That implies that you have been identified on radar.
If you are going through an airfield Control Zone you will probably be under an Approach Control Service or a Basic Service. In which case you do not need to be identified, you do not be told of the type of service, it is assumed that you as a pilot know the rules of being inside Class D airspace, know how to navigate according to what clearance you have been given and know how to report your position.
There are plenty of occasions when you might go in and out of Class D VFR and not be identified on radar. Under Standard Entry/Exit lanes or VFR routes for one. Low level pipeline inspections, helicopter work etc...
Now if you are crossing a Class D Airway or a TMA then that is another matter. Generally you will be higher (FL70+) so there is more chance that you will be spotted on radar and you will be mixing it with lots of commercial air traffic. If the controllers can squeeze you through, then you might get a VFR clearance, but it will probably be with the backup that you can accept an IFR clearance if required. In that case I would expect you would be identified and told you were under Radar Control (to re-emphasise to you that you are in a different environment). But if they are busy the last thing they really want or need is someone doing 100kts at FL80 inside the sector for 20-30 minutes ... it can make every arrival and departure subject to additional co-ordination/climb/descent or vectoring.
What you won't get (and shouldn't get) are Deconfliction Service or Traffic Service inside CAS. If you have, then I suspect it is just a momentary lapse as the controller tries to assimilate yet another change of rules ....
Hope that helps.