Why would Safelite or Belron need your services? Couldn't they just access the OE tools and perform the scanning and calibration themselves?

Belron only handles calibration, not the pre and post-scan. They could do it, but they would need to purchase every OE tool for each van and location, which is very costly. OE tools range from thousands to tens of thousands of dollars. Economically, it's challenging. AsTech had all the tools.

Did AsTech use more aftermarket tools or OE scanning tools?

AsTech tool acts as a modem. It connects the car over the air to the tool. With a bank of 10 tools, they can reuse them. A company like Safelite lacks this patented technology, so they can't replicate it. They would need a tool for each truck, which is cost-prohibitive.