Correct observations. But have you wondered why those solutions are ineffective?
Kids nowadays use phones and tablets for the most part. They don't even know how to use a computer that well and are not taught properly. But this isn't really on the kids.
Now, suppose I'm an OS developer. I cannot simply fork Android or iOS to create a child-friendly toy operating system for smartphones with a reduced set of features. The hardware is locked down to oblivion. They want you to use their OS. And their OS has no user accounts, permissions, or firewall configs.
Well, then suppose I'm an app developer, and I want to make a browser or social app with built-in client-side content filtering. But my browser doesn't pass Cloudflare or whatever attestation, and is blocked from half of the sites. It might not even be approved on their app store so people will never find it.
Fine. Then I want to change what content is filtered within the approved apps. But those options either don't exist or is some kind of cloud service where you give them your age, and they decide what to filter.
========= Parents can't even control what software runs on their own hardware. How are they supposed to control what runs on their child's hardware? =========
"The market failed", so they can sell you parenting among other things as a service, with surveillance as a free gift. The tech companies make money while the government gets control over the populace. It's a terrible arrangement.
That is why most digital parenting solutions you've seen are ineffective or can be easily compromised. Tech companies along with the government are playing chess against you at every level of the stack. Don't ever forget the PRISM program exposed by Edward Snowden. Apple, Google, Microsoft, Facebook - they're all complicit. Don't look at what their PR department says, look at what they do: https://en.wikipedia.org/wiki/Edward_Snowden#Revelations
One possible short-term solution is antitrust legislation for hardware vendors to ship their devices without an OS... is what I would say if we lived in a sunshine and butterflies world. Maybe the EU is not thoroughly captured yet and still has the ability to implement this, but I doubt it. Technoauthoritarians are building a panopticon to contain the sheep, and they're not even hiding it at this point:
https://www.youtube.com/watch?v=sQqQtgRdjZU https://www.youtube.com/watch?v=d34b7taQ640
The actual long-term solution is difficult. We have to make our own computers and radio equipment before they outlaw mining and manufacturing using the same safety excuses, which will happen when humanoid robots can do those jobs. The entire stack has to be open-source, which means we will have to diffuse fab technology everywhere so that people can manufacture computers locally, from mining to wafers to final assembly, in every city, or even at home. There are very talented people working on this problem, so it will be done. Just don't fall for the narrative that surveillance is inevitable or needed.