steve wrote:
Of course it makes the lights on the control panel look evenly spread
out.
However, you failed to explain the logic of holding a train *full* of
people.

Because they enjoy causing more delays e.g. On the District line:

Train crushed-full but waits in the station slighlty longer, a couple
more people squeeze on each door and the doors just manage to close.
Train moves off, people fall back slightly thereby forcing the door
open slighlty so train stops. Repeat several times. Driver announces
"I know its packed in there but don't lean on the doors..... Fine if
your gonna lean on the doors I ain't going no faster than this {in
rather abrubt tone} ... etc.".

A few points

* Net effect is to delay that train and cause the one behind to have to
queue so holding the train is counterproductive

* When it is that packed there is no option but for sevral people to
lean on the doors. Making unpleasant announcements isn't going to
change anything - opening the doors and asking people to leave might do
though

* Why can't the doors lock shut like they do on real trains (eg the new
Desiros on the Hounslow loop)