AnonyMint,

I can go pretty much with murraypaul's answer, thats how i would say things go.

The only thing that I thought about, regarding this so called (theoretically inexistent cartel in free market) cartel, is that they could attempt to mine their own transactions, and thus, having a buffer of transactions always being able to fill their blocks 100% with transactions, and thus mining more efficently...
As I current understood, each block has a certain amount of transactions, but they are not always 100% full... The trick would then be as a mining company to always have blocks 100% filled with transactions...and this will give you an advantage...and I guess this is only possible if you have a loyal backing that gives you all transactions and just is ok with waiting more than average for the confirmation. (so that there is always a buffer of transactions such that blocks are always full)...

Anyway dont know if the above written is correct, and also dont know if it has any serious implications. In anyway, they will have more than average delayed confirmation times. (not that this confirmation time is of any importance really to amazon or the customer)
So to become the biggest miner, they should then slowly increase their business, always being sure to fill blocks more efficient than others, with the backing of the obedient transactions of amazon that will simply wait untill its their turn....

Or is all above complete nonsense?