That calculator explicitly assumes a car-oriented existence in both places. Taking their 157% factor at face value, $10.8k for a car in St Louis is $17k in Seat

That calculator explicitly assumes a car-oriented existence in both places. Taking their 157% factor at face value, $10.8k for a car in St Louis is $17k in Seattle. So $80k without a car is equivalent to $97k with a car. Or $60k with a car is equivalent to $49.2k without a car in Saint Louis. Either way, the income level in Seattle is slightly better.