She set her autistic daughter, who might not be capable of doing better without outside help, up for brutal bullying on purpose because she wanted to "teach her a lesson".

Autistic people commonly have sensory issues. That includes things like pads.

They also often have executive functioning issues. That means something goes missing on way from intention to action, even if they really do want to achieve a certain thing (like a hygiene routine).

They can also have tremendous issues with things that change over time and mess with routines, such as periods. Some autistic kids can't even handle their teacher being sick for one day. Change freaks them out and overwhelms them.

They also tend not to understand social situations to tie point where she most likely didn't understand how she actually comes across to her peers.

So what does the mother, knowing her child has special needs, do? Does she look up how other parents have dealt with it? Does she try to find a way to deal with it that works for her child? Does she buy a parenting book? Does she ask her daughter's doctor or therapist? Does she ask her daughter what makes it so hard for her and how they might make it easier? Nope. She goes for pain maximization. And that's why she's a garbage parent.