I think this used to happen a long time ago on the Ohio turnpike. They'd look at the time printed on your ticket when you entered compared to the time you got off, along with the distance between the two points. Either that or it was a tall tale spun by my uncle to teach me how to calculate average velocity.

This is already deployed in Europe, and the UK.

True, some highways in the Netherlands already use a system like this.

Worst part is, in a stretch of road with for instance 15 camera's . they won't take the average speed between camera 0 and 14, they'll fine you for the most expensive one.

So:

if you average 100 Km/h from 0-14,

and average 115 Km/h from 0-5,

and average 117 Km/h from 8-9.

You get a fine for the 117 km/h

And, in any case, isn't much different than automated radar + photo tickets that have been implemented in some places in the US.