I guess my original statement should have been prefaced with a great big "if".
As in: IF you're concerned about what your child might read, it's still 100% your responsibilty to be the gatekeeper. Nobody else's. Be it physical OR digital media. IF a digital reading device (and the connected online store) makes it too hard, or too time consuming to do the monitoring you WANT to do as a parent... too bad, so sad. Deal with it or don't let them use the technology. There's no reason your child HAS to have a digital reader. People who never used an ereader before still fall in love with reading. Amost every day I'd wager.