On CRT screens yes, but backlight in LCD screens is LED/fluorescent driven by much higher frequencies. Though some LCD screens still flicker, but it is visible only on special patterns: http://www.lagom.nl/lcd-test/inversion.php
Not necessary much higher. I've measured screen flickering in Lenovo T500 (probably one of the oldest laptops with LED backlight) with small solar cell and oscilloscope and it's 220Hz, with lowest brightness setting only 100Hz (although this brighness level is not too useful):
http://commonemitter.blogspot.com/2017/06/lenovo-t500-measur...