Smart terrorists don't use cellphones because stupid terrorists do.
Theatrics to make it look like they are doing enough. Truth is, if someone immigrated or gets radicalized without detectio, the IC is relying on them not having good opsec. Spying on everyone (instead of with a warrant) , E2EE subversion,and these silly laws won't give them additional capacity when the actual terrorists and mass shooters that slip through already have bad opsec,don't use mainstream platforms or E2EE