Safety Knights

Legally, no. The ladder safety system/PFAS requirements that went into effect in 2016 only apply to fixed ladders >24 feet above a lower level. However, with that being said, I'm not a fan of cages at all because if you fall, in most case, you're going to hit the cage and still fall down, usually causing more injuries.

I agree with everyone above. If the ladder was >24' you are good as long as you do not modify (or repair) the ladder until the 2030s. Practically, after Dec 2018 if you modified the ladder the cage is no longer legal (for the portion modified, but you might as well do it to the entire ladder).

I too have never been a fan of the cages, and never been able to figure out why they were considered Fall Protection.

Don't forget at the top there should be a self closing safety gate as well.
Here is a great quick tip on the WWS standard and the changes that took place in 2017. It does a nice job of outlining roof safety requirements as well. Getting up the ladder safely is only the first step. :)
https://www.grainger.com/know-how/safety/walking-working-surfaces/slip-trip-hazards/kh-safety-walking-working-surfaces-rule-398-qt

You have a few options, technically speaking in California any fixed ladder, more than 20 feet will require a cage, well, or a fixed ladder PFAS. In some other states, this requirement should be met with fixed ladders above 24 feet in length.