My own personal take as someone who actually commuted on 85 with my wife and saw more and more Teslas on the left lane as the years went on, is that electric cars being allowed on the carpool lane provided a huge initial boost to Tesla sales. All the rich folks buying Model S so they could avoid traffic.

But I am bitter. I was actually commuting with 2 people on the car while rich folks bought their way there (totally on purpose, so the electric cars become more popular, I know)