You bring up a good point. It's common knowledge that most countries have laws about spying on their own citizens, but not citizens of other nations. Furthermore, global intelligence organizations freely share intelligence. They have been using this "loophole" to effectively spy on their own citizens by proxy. It seems that it's in the best interest of all citizens of the world to form some sort of treaty that says they want spy on each other without due process. It's seems pretty counter intuitive that my own government would encourage, and even assist another government to spy on me. Isn't the main purpose of the government, the reason that I let the government exist in the first place, to protect me from foreign threats. Certainly another country spying on me is a threat worth protecting from.
Not sure why this is getting down voted, it isn't hard to understand or show evidence of. You may not agree with it, but it is fact. For example a Columbian drug lord can break American laws without ever stepping foot on US soil. A hacker in China can violate wiretapping laws. The sovereignty of other nations has given way to extradition, extraordinary rendition, or even drone strikes.
There are other examples. This is the one that came to mind most readily. I don't smoke up. I don't support Marc Emery. I was however, ashamed at how nut-less my government was in handing him over.