>it seems as though a 17-year-old in a tech role would be unable to access a corporate network if it was protected by a VPN.
That's not what the law states. The actual law states ...by prohibiting the provision to children in the United Kingdom of VPN services which can facilitate evasion of OSA age-gating processes so a corporate network protected by a VPN doesn't fall foul of the regulation.
>Given that children can generally work from 13
Not in the UK they can't. Children can work part-time at 14 however they can only start full-time work once they’ve turned 16.