It's very easy to watch other people and think 'that's where they are going wrong. But that could be a misapprehension.
My sister was a brilliant nanny - fun, firm, supremely confident, managed a family including baby twins + 4yo with DS + 6yo and made it look incredibly easy. (Even though the mother travelled for work and was often away overnight for up to a week at a time.) Everyone had fun, everything got done on time and in the right way. And she wasn't a millionth as irritating as Mary Poppins, either.
Then she had her own dd... and she stumbles just as much as any other mother. Think my niece was about a year old when sister turned to me and said, God, everyone said it's harder when it's your own... My point being, that my sister's child-rearing skills are excellent but that doesn't make her Perfect Mum Of The Year. And my niece, while gorgeous, is certainly not an angelic child who is always perfectly behaved!
Equally, my childminder when I was little was fantastic. Again, fun but solid and stable, could rely on her absolutely. She was brilliant. And very strict about manners/behaviour, all the things that people think of as boundaries.
She has two sons. One is OK but the other became a heroin addict. (Thankfully now clean but there were many years of torment when he was in a very scary place indeed.)