Maybe I misread this but my understanding is that the algorithm is intended to have all lanes have the same flow rate. If one lane is slow, charge more on that lane to incentivize people to use the other lanes instead. If all lanes are flowing equally, they will be priced (mostly) equally.
In this case, the slowness was based on weather conditions and plow trucks not because all the traffic was on express lane and all other lanes were empty. Clearly, their algorithm needs to take road conditions into account when creating this prices.
I didn't read this as a premium to use the express lane or only allow rich people to get home, just an unintended consequence of a beneficial program finding an edge case.