You’re right, that is unusual, and interesting.
I don’t have a problem with it. The public highways are there for transportation purposes. The feature you describe aids transportation, because people don’t have to drive to the next exit, get off the Turnpike, and double back to their destination. That the people benefited are going to church, as opposed to some secular destination, makes no difference. The government should treat religion and non-religion equally.
I don’t see how historical documentation could help the creche guy. Just because something improper has been going on for a long time doesn’t mean it should continue. Ronald Reagan changed a lot of things that had been going on for a long time.
Right. But I was thinking along the lines of a written agreement or even a deed/covenant that permitted the creche to be placed there in the past under certain terms/conditions. That's what happened in the case of the church on the Pennsylvania Turnpike. When they built the Turnpike through that area back in the 1920s they needed to take some of the church's property under eminent domain, and the parking area and pedestrian access were built as part of the agreement for transferring the title to the property.