Looking at the raycast tutorial, looks like it is a ‘deliberate’ feature and that the API documentation is incorrect.
For the moment, I recommend adding filters to help get around this issue: Raycast through multiple entities
Edit: On a closer look, it looks like a trigger in PlayCanvas is just a rigidbody in Ammo but with no collision response: https://github.com/playcanvas/engine/blob/18bdc36d108031beca3fbfab948feb911eea2159/src/framework/components/collision/trigger.js#L54