Given that these are used for peering between different independent networks -- pretty much the definition of the "public internet" -- there shouldn't really be

Given that these are used for peering between different independent networks -- pretty much the definition of the "public internet" -- there shouldn't really be much expectation of privacy. At least not if you're smart about it. (Network taps aside, at that level traffic can often get redirected through hostile networks via BGP spoofing.) Hopefully any important information going through them is already encrypted.