Having worked in a first world school I was surprised by the lack of vandalism and theft.

It did exist but was very minor. But this is still enough for a large body of students to destroy a small lab over a few years.

But the main issue was game playing and entertainment. Kids will do what kids do everywhere, just play games when left to their own devices.

If you're taking away from other time this becomes detrimental time.

Here's a negative review on the hole in a wall scheme for instance - http://donaldclarkplanb.blogspot.co.uk/search?q=mitra

Not to say you can't design a system for kids to actually learn in unsupervised at a reasonable cost, just it's yet to happen.