What you're missing is that density is meaningless in a Western city. Consider a city like Tucson, which is really spread out. However, within 30 minutes I can

What you're missing is that density is meaningless in a Western city. Consider a city like Tucson, which is really spread out. However, within 30 minutes I can reach 500,000 people. In Phoenix, you are 30 minutes away from at approximately 1,500,000 people. Does that compete with NYC and SF? No. However, density undervalues western cities and overvalues dense ones. Unfortunately, there's no statistics for "people with whom you can have coffee within 20 minutes of travel."