Yes, Tesla benefitted early on the rebates - because they were actually selling vehicles. Their rebates ran out, but the Rest of the World now has that advantage over Tesla. Each company is given the same number of rebates - all they have to do is to produce a vehicle that the public will buy.
They’re catching up.
As for HOV lanes, the intent was to reduce smog. Reducing vehicle count by car pooling is one way, riding a motorcycle is another - which is why single bike riders can use the HOV lanes. EVs also further that goal, hence their exception.