Total recall is more than 20 years old, and they had full body scanners entering mass transit. Granted, that's a movie. It never really happened. But people were exposed to the idea a long time ago.

I don't think the idea was as far fetched as you're making it out to be.

edit (sorry)

There's also the whole issue of schools having the issue solved. I don't think that's true. Schools and classes are getting bigger. I'm not sure how trustworthy a roll call is in a class of 40. There are ways to mitigate that, of course, but why waste minutes a day when you can just slap on a cheap technical fix. The old way literally wastes days of instruction by saying 'here'.

edit, again, because i'm an ass (sorry)

If you're putting your kids in the hands of the state, it seems odd worrying that the state is monitoring their behavior closely. It's not like kids have rights. The state is charged with care of those kids, maybe it's a bizzaro solution, but it's a strictly audited and accountable solution.