Do work at home jobs really exists?

Yes, I actually worked from home for a software company for about a year in 2018-early 2019. It was just like working in an office, we had extension anyone could call that would go to our phone. They used Skype for Business that had like a chat feature, so the boss would send random text they expected you to reply to quickly. So they had ways to keep tabs on you. Also if you didn't move your mouse on your computer after 5 minutes it showed you were away from your desk to the whoel company. So they had sophisticated ways of tracking you. All in all though what I found is that the workaholics dominated because that's the workaholics dream, to just sit at home for 12 hours a day and work. And the company didn't stop them (and even promoted over work). So really the working from home ended up being more work than a regular office job.

Yep, and they're a lot of work.

Yes. I have worked from home for over five years.

The sort of jobs which can be worked from home would need you to have qualifications, experience, pass an interview and get regularly quality-checked.

If it's a job you just get by applying for it, you don't need any skills or qualifications, you don't get interviewed and anyone could do it, it's probably a scam.

I used to write and maintain programs from home for manufacturing and Oil & Gas companies but had to drive in on demand - a 100 mile round trip. If you don't produce results to expected standards you don't get to do it for long. You need to have impeccable work ethics.

A few, but most of them are scams.

Yes. There are many work at home jobs. Several of my friends work from home. One is an insurance medical adjuster, one is a workman's comp. nurse, one does something on computers, not sure what he does.