OP may send their child to a private secondary school, like 18% of secondary school students in the UK. Private schools tend to have kids from wealthier backgrounds as well as the resources to provide devices to those who can't afford them.

A friend of mine works in a boarding school where the pupils are provided tablets in order to do their work, join video calls etc... .

Can't speak on behalf of GP, but I suspect when they said "require," it's more loose than that. I've experienced UK schools that have a shared pool of iPads for students who haven't got a compatible device (for a multitude of reasons). So in that sense, students "require" a device from the perspective of learning, but don't "require" to own one outright (so it's not a barrier to education).