Sixty seconds is really not very long, especially at Union where the CSA may have to close doors on both sides and deal with the ramp. I haven't seen a train close its doors and then perversely sit there counting down. Arriving in that last minute is indeed cutting it close, and I would say, sometimes you make it and sometimes you don't.
60 seconds may be reasonable for the trains which have doors open on both sides at Union, but it is not reasonable to apply that same rule to the entire network when it requires the majority of trains to sit still with the doors closed for 30+ seconds. If you miss the train and it still sits there for a couple seconds after closing the doors, people will mostly perceive it as bad luck that they missed the train. But if it sits there for 30 seconds, they will perceive it as sabotage, and they will resent GO Transit. Which is not good for business.
Furthermore, requiring passengers to arrive at the platform 30 seconds earlier than necessary makes all trips on average 30 seconds longer, which adds up to a huge amount of wasted passenger time across the network. Wasting passengers' time is also not good for business.
Consider some alternative strategies:
Option A. Doors close 30 seconds before departure. Trains with doors open on both sides depart Union 30 seconds after the scheduled time. This is accounted for in the internal schedules.
Option B. Doors close 30 seconds before departure, except for trains with doors open on both sides. In that case, the first side does close 60 seconds before departure and the second side 30 seconds before.
B1: Only the platform which remains open last is listed on the departure screens. The other platform is used primarily for unloading.
B2: Both platforms are listed on the screen until a few minutes before departure, then for the last couple minutes, only the platform which remains open later is listed.
Option C. Doors close at the departure time. The internally scheduled departure time is either 30 or 60 seconds later depending on whether doors are scheduled to be open on both sides at Union.
I recently found that similar restrictions are in place elsewhere.
The procedure in the Netherlands is that the doors start to close 20 seconds before departure. I am very aware of this, as I would routinely arrive on the platform within about 40 seconds of the train, and I needed to account for the seconds. This is not a reckless practice, it is a rational and beneficial behaviour in an environment where both trains and streets are incredibly predictable, and everyone's (phone) clock is in sync with the railway's clock. To further facilitate this behaviour, NS provides clocks on every platform which show the seconds.
In practice, it took about 18 seconds to close the doors and the train would sit for about two seconds before starting to move.
When I was in London the National Rail stations in the area had signs indicating that doors close 30 seconds before departure.
The Eurostar is not a similar restriction, because passengers need to go through customs, and at some stations (Lille, Rotterdam and Amsterdam) there are not physical customs areas like you'd find at an airport. All of the passengers first need to go to the platform and clear customs which puts them into a locked area. Once everyone is in the secure area, staff seal off all the entrances to the platform, and then finally the passengers can be released back onto the platform to board the train.
