First, a short review of the history of telecommunications technology.
Initially, there was a flurry of inventors, inventions and companies involved in early telephone devices. Many companies would limit connections to only those customers that were using that same company’s equipment and service; hamstringing customers who did not use the same telephone vendor as some of the folks they would like to call.
In the USA this cacophony was solved by the government creating a regulated monopoly that became AT&T (American Telephone and Telegraph; a.k.a., Ma Bell, the Bell System). In other countries, around the world, it became an agency of the government: the PTT (Postal, Telephone and Telegraph).
The USA did not incorporate telephony into the government, but did become (by far and away) the largest customer; asserting its interests over the development of telecommunications in this country. The USA also became the largest market for telephone services and led development trends internationally as well.
Circuit switched, recoverable, networks were encouraged by the War Department (precursor to the DOD) as an asset in prosecuting wars. Packet switched data transmission was given a tremendous boost by DARPA (Defense Advanced Research Project Agency, an agency of the US government) when it worked with the private sector to start ARPAnet in 1969; the basis of the Internet.
Now, given the direct and indirect influence of the US market and the US government's role in the growth and development of telecommunications... It should come as no surprise to anybody that an agency of the US government (created specifically to spy on the entire world; technically outside the US borders) with the talent, technology, budget and inside knowledge of all the electronic means of communicating (through out the entire world) has succeeded brilliantly.
It should be mentioned that time and again (leaking bureaucrats, whistle-blowers and authors of fiction and non-fiction media) folks, like: former national security analyst (to multiple US Presidents) and author: Richard Clarke; Pfc. Manning; civilian contractor to the US government: Ed Snowden, have warned us that we must watch the watchers.
They (the NSA, in this case) are tasked to do a very difficult job and we've allowed them great power and authority to do the job. The NSA is an agency of the Executive branch of the federal government and therefore it is the assigned task of the Judicial and Legislative branches of the federal government to monitor and restrain said agency. It is the job of the citizens to oversee that the whole process is running efficiently and effectively as intended. Since, over and above all else, the day to day function of the NSA is necessarily done in secret, the citizens don't have the information needed to do our assigned task; enter the whistle-blowers, authors and leaking bureaucrats!
Citizens can take small comfort in the fact that very few, possibly no, other organization has abilities developed by and for the NSA, because on a daily basis many of us broadcast this information using the Internet toys and tools to which we've become addicted. Also, if you will, carefully note the information we make available to private entities (friends, business contacts and companies) in innocuous comments and shopping.
Congratulations/OMG the NSA is on the job!