Why do you only try a consequence once? When a kid doesn't turn in their homework, they stay after school. The next day they don't magically have their homework because they've learned their lesson and are walking a straight line now. Rather, they end up staying after school for weeks on end until they finally realize they'd rather have their afternoons back.
When a toddler throws a temper tantrum, they sit in the naughty spot for 3 minutes. Then they throw another tantrum--you don't say, "Oh, guess the naughty spot didn't work", and try something more drastic. Rather, you maintain consistency and continue for a period of time until you see improvements.
When your dog is constantly barking at people on walks, you don't decide that clicker training is faulty and reach for the shock collar--you keep at it until you start making progress.
Why is this girl different than all those examples? Why is grounding or taking away a phone only worth trying once?
As for the job thing, I have no idea where this family is from, but around here it's near impossible to get a job before 17 or 18. Even the baggers in the grocery store are college kids.
And even if shooting a computer and humiliating your daughter online does stop her from writing rude things online, it's not going to stop her from whining to her friends about her parents. It's not going to make her love her father more for helping her better learn to deal with challenges. It's not going to make her a stronger young adult who is better able to handle things when she's frustrated. I don't see a benefit to it other than she can no longer type on the computer. (How many times do we preach "don't hit the dog when it growls, or one day it will snap? This girl's just been "hit" for "growling"...will she one day "snap"?)