How much do you think it costs to make a pair of Nike shoes in Asia?

I've always wondered why the supply chain has exponential price increase at each step. The example given (guessed at) is the factory produces the shoe for $12.5 and sells it to Nike for $25. Nike then sells it to Footlocker for $50 and they then sell to a customer for $100. Everyone expects to mark up their costs by about 100 percent. Why is that the case? Even if we say the markup isn't 100 percent, why is it a percentage of cost at all? If the shoe factory can make $12 then why can't Nike and Footlocker both make $12 and retail the shoe for $50?

I'm not saying things should be different, just wondering why it is the way it is. If Footlocker was also selling some cheapo shoe for $50 presumably they do the same amount of work to bring that to the store. Are they only paying $25 for those? Why does it cost half for them to handle a cheaper shoe?