They could run foul of anti money laundering legislation.
Also, I could use my UK Adsense earnings to advertise an off-shore business and not declare my Adsense earnings to the UK tax authorities. If I do could the UK authorities consider Google a partner in that deception? Lots of things for Google to consider.
But I do hope they work something out, I'd be interested in it as well
(No, not for money laundering reasons!)