Why dont parents flying with babies and toddlers ask their children to keep quiet?

Bit of a rant here, but the aviation part is towards the end.

I had a flight from Chennai to Mumbai this afternoon, was totally exhausted and couldn't wait to come back home. To my shitty luck a family of 3 sat behind me with a daughter of 3 or 4 years old. I had to bear that IndiGo predeparture music AND this girl blasting songs at FULL volume on her parent's phone. While taxiing I finally asked the father to put the volume down. THANKFULLY he complied with my request(would have been better if he understood that I was actually trying to ask him to turn it off but my fault I guess). I'm surprised the parents didn't care that their daughter was blasting music at full volume and had zero compassion for the tired passengers around her.

While cruising this girl CONSTANTLY KEPT TALKING AND TALKING AND TALKING in a high pitch and a loud voice and sometimes shouting at her father. I didn't get one minute of sleep on that 1h25m flight.

Here's the worst part: when we started our descent into VABB the girl started kicking my seat like anything, and yet again the parents didn't notice shit, or they let her do it which is way worse. Finally, when we were on our final, I turned back and asked her(quite politely) to stop kicking my seat. To which she started crying like there's no tomorrow 😂😂, thankfully the parents actually cared this time and tried to calm her down successfully.

Now to the conclusion, obviously I don't have anything against the girl, she's only a baby and children tend to do these kinda things, even I might have been like that as a toddler, but atleast my parents didn't turn a blind eye to me and let me blast music to the whole cabin. But I do want to say this to the parents of the girl, YOU ARE DOING A HORRIBLE JOB! BE BETTER PARENTS!

Here's the aviation part:

1)why aren't parents of infants asked to sign a waiver during checkin that declares that the parents will try in their full capacity from restraining the child from disturbing the whole cabin? This sort of incident has happened to me many times but all of them except this one has the baby sat at a distance from me.

2. why dont indian airlines introduce quiet spaces in the seating areas where nobody below a certain age is allowed to sit? This has been done in some southeast Asian airlines. I can't imagine sitting like what I just experienced in a long haul flight for 16 hours. I would actually cancel without refund a ticket I paid lakhs for than endure it.