Those tires aren't bald -- there's plenty of rubber there. They just don't have the tread patterns that street tires do for channeling rainwater.
On smooth dry pavement, those tread patterns are unnecessary, and in fact reduce the contact area between tire and pavement (and therefore traction).
The tires used on those race cars are ideal for the conditions.
Now, if they ever get rid of rain delays and just keep racing, then a different tread would be needed.
Finally, finally, someone has answered this question that I have been asking for a long time in words that I can understand. Thank you Steve0113.
Ok Steve, if it is smooth and dry outside as I was coming back from Virginia Beach to Hershey last week-end, I don't need any tread pattern? I would have loved to reduce the contact area between tire and pavement (and therefore traction). Gees, maybe I could have got one more mile per gallon.