I think one can excuse them from not securing themselves against their own government physically tapping their internal network.

It's referred to as "their internal network", but these taps were not within their buildings, as far as I recall. From my understanding, these are still leased lines run externally from facility to facility. It's been generally assumed that nobody is between points A and B on that line, but the line is still largely traveling through unsupervised space, and we are not the only government to have invested significant resources into tapping lines. (I believe both the US and Russia has submarines specifically designed to facilitate tapping undersea cables.)

and don't forget that most (all?) modern lines have been funded directly by the US government. For all intents and purposes...they are government owned.

Their own government is just what we know about. You really think foreign governments weren't doing something similar? Why would you think that?

We most certainly cannot excuse them.