As a foster parent of over 15 kids (not all at the same time)... here's what I need in a phone plan for my kids (so far I've not seen a sinlge plan that comes close - but hopefully I'm wrong)
1) Kids plans that use OpenDNS.org or similar content filtering for kids. I don't want my 12yo watching beheading videos rights next to porn - it's just wrong! Looking at you kaotic.com. Different profiles for different age children - I've got from age 2 to 18 in the house.
2) Ability to setup schedules for data usage. A school-schedule and a school-holiday schedule, where you can customise exactly which hours of the day, a child can/can-not use the data. I cut their WiFi off automatically from 6pm to 7pm to force them to interact with the family during dinner, do homework, showers, etc. I don't want my 12yo using data between 8:30pm to 6:00am.
If a child has engaged in risky or inappropriate behavour online, I would like to suspend their data priviledges for a few days or week. I would name that schedule "no data".
3) Optional) Ability to track my childs location even after they burn all their data. If my child is kidnapped because they have been watching porn, hanging out with older men online at 3am and then go missing - then I want to track them regardless of data usage. My kids have been known to show up in a different town without me even knowing they've left the house!
4) Optional - Ability for parent to blacklist or whitelist phone numbers on the same web portal that does content filtering and schedules. Known people that will cause harm or have mental health issues, need to be blocked.
ANY Telco that provides all this, could easily sell such a package to every foster family in Australia, and also do deals with all the foster-agencies for home internet.
Last time I checked a competent network administrator was smarter than a 12yo.
Its not a matter of who's smarter, its that the current technology (and even laws for certain elements) does not make it possible at the moment in a single all encompassing system.
"Last time I checked a competent network administrator was smarter than a 12yo."
The problem is that there's a very few of the former and a very lot of the later. What your asking for is a very niche product (that in most cases doesn't work anyway - I should know, I'm a competent network administrator with two 12 year olds 😀). There's already a massive industry built around "protecting" the children. If Optus (or any Telco) could do it and make a buck then I'm sure they eagerly would.
If it helps any, my suggestion is to look towards your (our) own biases. We've all grown up in a world where information (I use that word holistically) came via the gate keepers. Our parents could easily control everything we knew about the out side world. Governments and schools and the media also held the remaining the keys. I'm not saying this was a bad or good thing but just how it was.
These days as parents, we seek to emulate that familiar (and powerful) approach. But IMO that horse has bolted. Its a fantasy to think we have much control over what our children consume after about the age of 12. If you shut down their devices then they'll just hot spot off another kids phone or even just look at what's on their screen. They'll also view us as a barrier that they need to bypass and hide stuff from - if they do get in over their head we won't be the one's they turn to.
I'm not saying its all hopeless but it is all very different. Obviously the issues you face as a foster parent are also unique and no doubt challenging and rewarding. We don't have to learn how to navigate all this information growing up (the good and the bad) but kids do. IME the old approach of lock it away until they're 'ready' isn't protecting them in the long term.
Anyway, its a good request and maybe Optus will take it on board. However they (the industry) don't seem all that interested in trying to limit those that are or will shortly become their biggest customers (either themselves or their parents buying data for them). I remember thinking years ago how useful it would have been to have a mobile plan that only cost say $10 a year. Phone calls could be charged at say $2 a minute. That way you could give kids an way to contact you (or the reverse) when it was really important. But that simple protective option didn't happen back then, all the Telcos charged their $30 a month minimum.
Good Luck - at least you'll have the chance to try out some different strategies on different kids. I only get one shot navigating ages 10 to 20 with mine. Should be a wild ride 😀