Generally rally routes are kept fairly secret, except NORRA Mexican 1000 which is run slightly differently than a true navigation rally. For sure the routes are secret for Sonora Rally, which travels in a lot of places where there is and has been no other off-road racing. One thing to consider is that often the routes pass through land that requires special permissions from ejido owners, special government permits, and possibly temporary opening of normally locked gates. One way of obtaining access to those special places is to assure there will be little or no vehicle traffic before and after the event to minimize impact to the roads and trails. I can't speak for baja rally, but they do promote the concept of minimizing impact to the terrain. And I have never seen them publish their routes in past years.