1. Transit agencies have no way to reasonably validate what the future holds. From the standpoint of today, a hydrogen bus can be expected to replace a diesel bus 1 to 1, while battery electric is a 2 to 1 replacement. This might not be a huge issue except:
2. FTA regulations have strict requirements on how many spare busses may be kept at any time (defined by the ratio of peak vehicle usage vs the size of the overall fleet), doubling the size of the fleet blows this ratio out of the water.
3. It doesn’t matter what BYD offers or what’s possible in China, US transit agencies are required (FTA regs again!) to buy busses made in the US. American manufacturers do have somewhat decent battery electric products, but they are clearly not at the leading edge. With the proterra banktrupcy, there are limited competent suppliers in the market. To a large degree, gillig et al do get to decide what gets pushed into the market.