suavojr, that's right. I suspect social conservatism and the non-interference with religions. But Canada requires all charities who get the tax breaks to publish their financial accounts. Other countries require this transparency as well.
Write your Senator or Congressman. Start a petition.
The US list of charities:
http://www.irs.gov/Charities-&-Non-Profits/Exempt-Organizations-Select-Check
Canadian: