Cam-followers are manufactured from a limited number of steels [and some durable plastics], with rigid quality control and testing. Industrial Cams are manufactured by machine builders with different design and manufacturing quality standards and procedures. Thus, even though a cam is an easier machine element to analyse, it is left to the machine designer to choose the correct material, heat treatment and lubrication method to give the cam a life as required by the machine.
The operating contact stress will generally be higher than the nominal contact stress that we derive from the Hertzian Contact Stress calculations. For gearing, it is normal to apply a number of 'Track Loading Factors' that account for nature of the drive and load 'smoothness', dynamic effects due to the stiffness of the gear tooth steel and deflection of the gear tooth, as well as alignment across the gear tooth, and consistency of gear teeth from tooth to tooth.
These can be applied in the same way to the nature of cam-contact.