It is also scripted. Google used to use internal people do to the screening but not anymore, they have outsourced it to agencies. And a random recruiting agency drone on the phone, paid minimal wage, can't be expected to ask sensible questions, so they get a script to choose questions from, along with expected answers.
I doubt Google has outsourced their entire process.
But many recruiters work as independent contractors or in recruiting firms. They often do a minimal phone-screen, vs sending a candidate "cold" to the hiring company.
