Dave, You are preaching to the choir. Many of your viewers are technical people! You've addressed the drop in efficiency when the cells are installed flat, cars covering a third of the surface in heavy traffic, and the effects of dirt. Add to that the shortening of the solar panel's life by exposing it to foot, bike or vehicle traffic. We get it.
Unfortunately, the people paying for the road are not technical, and want a quick fix for their constituents. Everyone hates paying for road maintenance, and solar roads look like path to reduce this burden. If their advisers can't cite specific reasons as to why it's wrong, the politicians believe it's perfect and will last forever, which, of course, is only the two or more years they have in office.
One technical item:
What's the change in stopping distance of a vehicle on a solar panel? Is the glass surface far better than glass bridges in Venice, Spain or China? Are the surfaces of the solar panels some form of non-slippery transparent aluminum? (Aluminium in Australia) Or transparent concrete? Of course grit will help, and it looks like some of the grit on the bus lane was ground-up solar panel!
The trial lawyers (barristers) are in the wings, waiting. Reducing the speed of the traffic or posting signs to increase distance between vehicles on solar roads will be considered an admission of foreknowledge and liability in court.