This is false, and the ACLU should take this page down. In fact, in the 1970s, the Border Patrol tried to rely on this notional "sphere of influence", and was smacked down by the Supreme Court. Searches concomitant with the Border Search Exemption must have some nexus to an actual, recent border crossing.

This is claimed by DHS and not backed by law or legal precedent in the manner you imply.

ICE and CBP do conduct arrests pertaining to border violations within that 100 mile zone, but they aren't shaking down random passers-by for their iCloud passwords. They do have to follow due process.

I don't have citations because I can't prove a negative.