Tax is depends on seller agreement + location, as be4 wrote, but if do purchase no matter what good I have no extra charge but g1 probably in purpose charging to decrease fees for transfers, tax or widraw.
in cases transfering money not same country moustly cases fee apply, even friend transfer, depends on country from and where. Purchases for goods/services should not be apply fee as this is sellers duty and he do profit... Some seller trying bypass via adding extra costs...