Yes you can trivially tap a fibre -- https://www.gigamon.com/products/access-traffic/network-taps... for example

You can even do this without breaking the fibre

What you can't do is ship 80% of the traffic across the world to the US without either the ISPs agreeing, and thus a conspiracy of thousands of people in thousands of ISPs, or doing it outside the data centres, meaning millions of taps in various ducts around the globe, which would be found on a daily basis.