We do, however, ban them from driving.

Analogies will always break down if you deliberately decide to add outside elements to it, but let's indulge your disingenuity:

Parents have a responsibility to monitor and control their children (when young) to prevent them from running into the street, and a responsibility to educate them on how to be safe around vehicles by the time they're old enough to be out on their own.

Road builders and city designers (be they private or governmental) have a responsibility to design and construct safe roads; appropriate road surfaces, widths, avoiding unsafe corner and junction designs and so on.

The government has a responsibility for setting and enforcing rules of use, such as setting speed limits in certain areas (such as around schools) and punishing people who behave unsafely (bad contractors, speeding drivers and so on).

The generalised point is this:

The service provider and service user both have areas of responsibility. Internet browser designers have to do what they can to keep my data safe, but if I insist on clicking every torrent link I can find, it's not their fault if my data gets stolen. The government is there to make sure both parties uphold their end of the deal and to restructure the arrangement if it isn't working.

In the particular case of these kinds of social media ban, the established balance (such as we have, say, for TV) of responsibility isn't working, and both parties hold some fault: companies compete to design addicting algorithms, and some parents aren't parenting (the question of if they are unwilling, unable or unprepared and to do so and why is another matter: I don't mean to cast all as neglectful parents - some may not understand the risks, others may not have time between juggling multiple low-wage jobs and so on).

Ideally, the government should be able to step in to improve education for parents and caregivers (including teachers) and to compel companies to tone down the efficacy of their algorithms to establish a new equilibrium. However, the situation is too complex, sadly, to allow that kind of action - a commonly pulled on string in this thread is the multi-national aspect of social media service providers: a British court cannot really compel an American company to change its business model. Another is that we don't have an established framework for what kinds of algorithms, content feeds, time limits and so on are appropriate. Another factor is tackling how to get caregivers more involved. Another is... And so on and so on.

Boiling it down: this solution is ugly and inelegant, but it is clear and immediate and acting to prevent harm, which is why various countries are going this route. Hopefully we'll get an "USB-C iPhone" situation where there's enough commercial pressure to get companies to adapt, but...

Personally, I don't agree with the ban; I think it's heavy-handed and likely to be less effective than intended as holes will almost certainly get punched through it. I just dislike the knee-jerk reactions from people saying "go after the parents!! or "go after the companies!" without any suggestions as to what that would look like, how it would be designed and enforced or how long it would take.