As 'rayiner points out repeatedly, there is plenty of precedent for people being forced to turn over information in their possession to comply with government investigations going back centuries.

This is much different than requiring that arbitrary third-parties to be compelled to take arbitrary action to assist in a government investigation. Where they are required, it is a power granted by statute with limited scope. (Phone companies are required to assist in wiretaps via things like Communications Assistance for Law Enforcement Act; I forget that was in effect before that. And they get to bill the government for it.)