Its very simple. Look at the profit margins of those companies, there's simply a lot more to share.

If you don't need to buy a product to make a product, or when you have to that's typically pennies on the dollar you can share a lot more of that.

The real difference here is that when the market is favorable you CAN share more. And Samsung is doing so. In the US you probably wouldn't be able to do this because the shareholders will cry and will happily give a 100M bonus to whoever will 'lead' the company better. Where better means diverting as much as possible to the shareholders