The Manitou Incline crosses land owned by the City of Colorado Springs, the Pikes Peak Cog Railway and the Forest Service. For liablity reasons and because of parking issues, the Pikes Peak Cog has tried keeping people off the Manitou Incline. It hasn’t worked and thousands of people hike up it.
For more than a decade there have been several talks to make hiking the Incline legal. So far all of them have fallen through. Currently nearly $100k is being spent to study how to make it safe and to deal with the parking issues. Manitou Springs has an information page on the ongoing meetings.