I suppose right now there is a lack of supply of DH in HK right now. Many families have an immediate need for a DH and there isn't enough. When I interviewed my helper, she had back to back interviews and a choice of whom to work for. I did not want to get a newbie and was pleased hiring an experienced DH this time. (20+ years in HK)
If there really is a problem, I'm sure it could be reported and investigated. I'm not saying there isn't a problem but I don't think it is as bad as you say it is. But why don't the 5-10 people on here do something about it? Create a support group for those helpers in bad situations, create an app or forum for DH to voice complaints and they could be looked at and a course of action planned. It could even include interviewing and matching these helpers with incoming expats who need help so the helper could say peace out and move onto a better opportunity with a documented complaint against the previous employer. There are things that you could do to help, but to say HK and it's people are bad is not a solution at all and it doesn't encourage anyone to want to help.
There should be no comparison to other countries, stuff happens everywhere and workers are exploited. But giving too many rights and benefits for simple jobs with no education/training creates issues itself. Entitlement, not showing up to work frequently. Some rules are needed otherwise it's a constant battle.
Also, there is a reason why jobs pay differently, but it seems a lot of people on this forum are highly upset about pay differences, so why don't you pitch communism. It's like you want democratic, you want rights as an employee. So what happens one day when you are the employer? Do you have a magical wand that can form a company with all processes and procedures in place and a healthy revenue chain to distribute to the staff? I mean come on...