Ah waiting for somebody to say it's all the b....... passengers' fault. 'Action' too often means completely incomphrensible screeching at passengers through loudhailers by platform staff as the crowd builds up. Try it from the other side .
Indeed. A classic happens sometimes at Canning Town DLR, with shouted messages in condescending tone to use the full length of the platform - then the train comes in and it's one of the periodic two-cars instead of three-cars, stops right at the end, meaning those who have politely spread along the platform are now well behind the train. Big crush at the back door, can't even get past to another door, further shouts to stand back because the DLR punctuality is reported to TfL to 30-second accuracy (as the automated system can do it) and that's more important to operator Keolis than getting people to their paid-for destination.
Regarding spreading along the train, on the Elizabeth Line that is stated to be easy because of the wide inter-car connections. Unfortunately those who propose this policy forgot that the main stations have been built with two entrances, at the far ends, and also forgot that the space to walk through the train is the same space that many passengers are standing in, preventing one from doing so.