Does Expert work?

[idio4]

I test expert policy and IDM policy. And after evaluating on this map

 env=MetaDriveEnv(dict(
        map='OCO',
        traffic_density=0.2,
        log_level=50,
        start_seed=0,
        num_scenarios = 100,
        traffic_mode='respawn',
    ))

IDM (rule-based) policy gives such results:
Mean score: 255.12 ± 201.10
Success rate: 43.00%
Average episode length: 362.87

Expert policy gives such results:
Mean score: 331.60 ± 189.03
Success rate: 46.00%
Average episode length: 543.17
Is it okay? (and I wonder why expert policy uses not usual observations, but from vehicle, which has 275 shape)