There's a lot of inefficiencies with historical urban planning. This isn't the 50's, a typical household doesn't have money for two cars. Developing cities with progressive features can better accommodate people dealing with today's issues.
Urban density makes public transportation feasible, while giving people other options such as walking and biking. Mixed use zoning is a big plus, reducing commute distances. Minimum parking requirements and excessive parking lot sizes are big negatives.
If a city can be developed so people don't need half the number of privately owned vehicles, this has all kinds of benefits. The cost of a second car means the price of the vehicle, maintenance, repairs, fuel, and insurance. A family with a median income or lower simply can't afford this anymore.
Just looking at parking spaces, they can be an enormous waste of space. Parking areas mean farther commute distances. They take up all kinds of property, thereby driving up land costs, as well as the costs of goods and services. Longer commutes mean more wear and tear on vehicles, as well as more fuel and repairs. Also, more infrastructure costs as roads are needed to cover the extra distances.
