Imagine an employer who has a choice between two otherwise reasonable candidates, one of whom interviewed independently and one of whom had a parent with them. Which one seems more prepared to work independently? Which one do you not have to worry about mom calling to complain about their schedule or some other matter?
Unless parents let kids do things on their own, the kids cannot become independent adults. Even if they fail at something, that's part of learning to be an independent adult.
That doesn't mean abandoning your kids. Parents can prepare their kids for job interviews if they want to - just buy a cheap used copy of a book of interview questions and drill them. Teach them how to dress, how to shake hands, and how to look the interviewer in the eye. Warn them of red flags to watch for. Make sure they know they're interviewing/scouting the company even as it's interviewing and scouting them. And be there afterwards if they want to discuss how it went.
But don't signal to the interviewer that your kid is not ready for the job by showing up to hold their hand and answer or ask questions for them.