When I'm looking for WSOP 2012 results payout structure, why some players paid taxes and some of them doesn't? Is their goverment getting this money from them? Is it about being illegal in their country?
These are due to IRS regulations, and it isn't taxes paid, just withheld. The players must declare this money as income, less any deductions, to the IRS and then they can have the difference returned to them. For professional players, if they had losses and expenses to offset some of these winnings, they might get quite a lot of it back - even all of it. That's between them and their accountant and the IRS, the casino is just required to withhold that money.
Some countries have tax treaties with the United States and there is no withholding. That is why some players show no tax - but they still have to declare these winnings in their home country and pay taxes there, the casino just isn't required to withhold anything.