How would the ISP know what pages you went to over HTTPS? Only the domain name would be available, through SNI/DNS.
With a fee, this requirement could then be waived.
Dystopian but technically possible.
http://www.csoonline.com/article/2865806/cloud-security/gogo...
Gogo didn't require installing a root cert, but they DID issue forged certificates to MitM connections to *.google.com (and others).
Also, remember "Superfish"? Their root cert was pre-installed by Lenovo.