I think this is a very multifaceted issue.
The cost of living is high, especially with rent and food, so I do understand why people stay at their parental home longer. I believe that if young adults (I’m not calling them ‘kids’; they’re not children) are doing this, they need to be contributing to the home - token rent, saving for their own future, helping out etc.
I think a massive issue is, as the OP describes, the chronic babying behaviour of some parents on their adult kids. Making their lunch, doing their washing, picking up after them, lifts to and from wherever they want to go, buying their toiletries, paying for their phone. It’s terrible parenting and has led to many young adults not being able to do the basics like phone a company about an issue or make a simple meal.
These issues are years in the making though. It starts with mums (it’s always mum, isn’t it?) reminding their teenager to take their PE kit to school several times. Then they forget. So what does Mum do? She rushes off to take it for them. It teaches them nothing.
You see it on here all the time. “AIBU to think midnight is too late for my 19 year old to be out?”, “Daughter has fallen out with me because I tracked her on Find My when she was at the pub”, “Son (28) hasn’t called me today, should I contact police?”.
There’s zero resilience, zero critical thinking, zero initiative from many young people now. They’ve never had to deal with the consequences of their own issues. You’re a failure as a parent if you’re doing this. Your job is to prepare your child for the world ahead. To give them the skills and interpersonal ability to have a good life, contribute to society and prosper.