But trains generally don't. Trains are signalled so the waits and delays take place between stations and not at the platform: it takes a while for the delayed

But trains generally don't. Trains are signalled so the waits and delays take place between stations and not at the platform: it takes a while for the delayed train to reach the next station so it won't just sit behind the first train and be of no use. The stop times for commuter trains are quite consistent because there's no onboard ticketing: people just hop out and then on, and that's it. Tickets are prepurchased or sold by the conductor while the train is moving. A good portion of the time spent at a stop is spent decelerating and accelerating and not only loading/unloading passenger. Even if there were no passengers, the stop time wouldn't necessarily be substantially shorter. There's no other traffic which helps keep to the schedules: this cuts down the sources of unexpected delays. Barring track and switch failures, the only source of delay is a huge crowd of passengers leaving and boarding on a single station. Even there, station platforms are quite long and even if some venue were to ooze thousands of people out to the train station at the same time, there's a limit of how many people can realistically populate the whole platform in between trains. So there generally is always some space on the platform to which the existing passengers can still exit, and people waiting on the platform tend to saturate available free space instead of crowding into an unpenetrable flock. Now, buses could use "soft signalling" to even out the distance between consecutive units. Using travel cards only (either with prepaid monthly periods or by having single-fare smartcard readers onboard) and allowing unloading/loading through all doors at the same time would help. Bus lanes and unconditional traffic light prioritization (bus always gets green light) for public transit are used in many countries. But there's very little to do about the capacity of a bus and the short length of a bus stop. Even trams are much better: they can take in 3x-5x as many passengers and tram stops are generally much longer, allowing the tram to operate with 6-8 doors instead of 2-3 like a bus. Tram routes are often heavily isolated as well, and run with at least some basic level of traffic light priorities.