I'm having trouble reconciling him showing Amazon as the lowest spender by far of the three with their place as largest player by far. Are they just tremendous

I'm having trouble reconciling him showing Amazon as the lowest spender by far of the three with their place as largest player by far. Are they just tremendously more efficient? I wouldn't imagine so given they're all essentially renting out a physical resource to their customers. Maybe I misunderstood something about the article?