@mintlily
"I don't understand how parenting by giving rewards for good behaviour and consequences for bad behaviour is at all abusive - what a weird suggestion from some people"
It's not so much abusive as a misunderstanding of how and why behaviours happen.
Giving rewards and punishments is predicated upon the idea that all kids "could" behave, if they just wanted to enough. That they have the necessary skills, they just lack the motivation.
This is, frankly, bollocks. Apply the principle to other situations where people struggle and it becomes obvious. If a person cannot walk, let's punish then every time they don't walk, and offer rewards for when they start walking. If a person can't see, let's punish them for failing to see and offer rewards for when they do.
What's worse is that whole class systems reward the kids who are already doing well whilst shaming those who don't have the skills, whilst not actually doing anything to teach those skills.
Imagine if your kid had been born with cerebral Palsy and couldn't walk, and as intervention instead of physio the school suggested a reward system. All the kids who can already walk get a sticker every day and a reward on Friday (golden time). Whereas your kid gets no stickers, and no reward on Friday. No one kearns anything, except that your non walking kid learns a sense of shame in themselves and feel "worse than" everyone else for something outside their control.
Now, autistic kids. They all differ, but struggling to understand NT social code is a common issue. This can manifest in difficulty managing their behaviour, a meltdown from frustration for example. The behaviour is just a signal that there is something they are struggling with, just the same as being in a wheelchair is just a sign that someone is struggling with walking.
So the reward system for "being good" rewards all those lucky kids who understand the social rules and have the skills to follow them. They learn nothing from the system, except that something they can already do intrinsically now attracts an extrinsic reward, which is not a great idea for life motivation. The autistic kid learns that they don't get stickers, that they fall short, that they are less than, and that everyone seems to think they "should" be able to control themselves if they just wanted to a bit more. But no one actually teaches them why it's hard, or how to control themselves etc.
If you wouldn't punish a kid who can't walk for not being sufficiently motivated to walk, then you shouldn't punish an autistic child (or indeed any child) for not understanding and being able to follow social rules.