Would it be disrespectful of me as a nanny to tell the parents how to parent?

I freak if baby is in wet nappies for 3 minutes

This is completely neglect! They should be reported by yourself and the other nanny. I know that may sound rough but you have to think about those children. They are being neglected badly by absent parents. That’s what I would call those parents. Children that age should be eating properly from plates and bowls, drinking from a cup, and almost fully potty trained. They should be a toddler bed too. Please do the right thing and report this negligence so these parents get the help they need and these children get what they need.