I agree with this. I have been involved in writing software for online standards based testing. The software was being used by schools. But, it never took off. After many years of bootstrapping, the founders sold the company. I can summarize from my experience that software/hardware combinations in the classroom was difficult to scale because of :
1. Not enough fund to buy the hardware.
2. Not enough interest from teachers to move to a software based testing.
3. Not enough pressure from school district to move to software based testing.
Just my .02 cents.