> While that amount of power is able to achieve 20MPH range, it does take its time to get there. In the US, with the open roads, that’s simply not enough power to keep up with traffic.
If you're talking about keeping up with traffic going more than 35 MPH, then the e-bike should have its brakes upgraded. I've gone down steeper hills before on my conventional bike at speeds up to 35 mph. With my cantilever rim brakes, it takes some distance to stop (quite a bit more than a car since you're effectively limited to a single wheel and a smaller contact patch relative to a car).
So if you have an e-bike that could keep up with 35 to 40 mph traffic, you'll still have to allow more distance to brake and leave plenty of following distance.