Infrastructure vulnerabilities make surveillance easy..
Weakness in digital communications systems allows security to be bypassed, leaving users at risk of being spied on.
Governments want to spy on their citizens for all sorts of reasons. Some countries do it to help solve crimes or to try to find "terrorists" before they act.
Others do it to find and arrest reporters or dissidents. Some only target individuals, others attempt to spy on everyone all the time.
Many countries spy on the citizens of other countries: for reasons of national security, for advantages in trade negotiations, or to steal intellectual property.
None of this is new. What is new, however, is how easy it has all become. Computers naturally produce data about their activities, which means they're constantly producing surveillance data about us as we interact with them.
Corporations are doing it for their own purposes; collecting and using this data has become the dominant business model of the internet. Increasingly, governments around the world are ensuring that they too have access to the data, either by mandating that the companies give it to them or surreptitiously grabbing their own copy.