> What are they even counting as a 'computer' to get to 70?

When I worked in the industry, we had four different CPUs of different architectures on one small (fit in your hand) circuit board, each running its own software and communicating with each other via buses on the board. This was for controlling one single function in the car.

Strictly speaking, I would say that single circuit board was 4 separate computers. It quickly adds up.