• Still not had an answer explaining how the US government inspecting communications crossing its borders, something it has always had the power to do within the constitution, offends the 4th amendment.

I guess I'm not quite sure what you're looking for regarding an answer on how it offends the 4th amendment then. :c)

• There's nothing to stop congress enacting data protection legislation and so no reason to completely subvert the intention of the constitution, as you suggest.

It is true that although the 4th amendment is only for the government, corporations have been evolving into quasi governmental organizations unto themselves.  The government could limit or regulate their data collection fairly easily since all they have to do is declare certain types of data collection by corporations on citizens illegal (the so-called right to privacy) and not even come close to the constitution.  So you're right there.  I was looking at the subject from a different angle.  The question would still come down to the political will to do so though.

• The IRS has been able to inspect all your financial records, including demanding them from your bank, for decades. Nought new*.*

Although true, it's still not watching every move you make on the internet, which is in extent now, a wiretap.

• How did you know? Do you work for the government?

I can neither confirm nor deny that statement. :cp  ;c)