Wandering traders and trader llamas does not have same spawning rules as animals, but they can affect the mob cap.

Steps to reproduce

1. Create a void superflat world
2. Press F3
3. Summon the wandering trader and trader llama
4. Observe the mob cap (C:*)

→ The passive mob cap is increased.

Observed result:

The wandering traders and trader llamas does not affect the mob cap.

Expected result

The wandering traders and  trader llamas can affect the mob cap.