What about signing up with temp agencies for office jobs. They can turn into permanent or at least contract positions, once they discover how capable you are. And in terms of unexpected contacts, I temped as a receptionist for a well-known head office during uni holidays. I helped a visitor with something unrelated to work, not expecting anything in return, and he said, "I hear you're studying law at uni. I have a contact at (named a big city law firm) who does their work experience and placement programmes. Would you like me to introduce you?" Of course not all temp jobs will offer great connections or opportunities, but the more you do, the better the jobs you will be offered, the more people you will meet etc.
I don't mean this to come across as knocking you when you're down, but some of your responses are coming across as rather snobby and aren't doing you any favours. If your daughter has the same entitled attitude, it can hold her back.
I'm also surprised you think it's the school/uni's job to teach your DD how to find work. It's a parent's job to teach their child how to construct a CV; how to write a cover letter; how to prepare for, dress and behave in an interview; how to write a brief thank you note following a knock back; where to look for jobs; help them develop self confidence etc.
All that being said, the job market is hard for everyone, but your DD is in a better position than most. She's young, presumably healthy, and has no financial worries or responsibilities. Her age means she's eligible for a working holiday visa in lots of other countries, where she may be more successful finding work. She could also do a shorter stint abroad, like a summer camp job. It might not be her ideal, but it's better than sitting at home moping. You've also been given good advice re Tesco - these types of organisations are massive with lots of different roles. Has she tried to move into any of these? A friend started off on checkouts in highschool, then moved into management and a senior HQ position following uni.
Contact senior staff in the companies she'd love to work for; talk to the parents of her fellow classmates; follow people on LinkedIn and comment on relevant posts; go to public lectures and socialise with people in the industry. What would you do if you were looking for a job? That's what your DD should be doing.