> If they can't kill themselves on a train, they'll just go to the nearest bridge.

This is a quibble in this context, but it's an important issue in others (such as access to guns):

Suicide is an impulsive act. The less "convenient" it is to kill oneself, the fewer suicides there are. A extra few minutes to reconsider can often be lifesaving.

This is well-researched (and still fun) podcast where I learned about this: https://gimletmedia.com/episode/guns/

Platform doors are not just for preventing falls onto the right of way, they also help to reduce litter, reduce delays due trains coming into stations slowly because of overcrowding and allow stations to be air conditioning.

In 2013 151 were struck and 53 died. Those are rather consistent numbers.

However, when you consider the millions that ride the Subway each day and the hundreds of millions each year it's a very small number.

Cars create more deaths per capita I believe.

> If they can't kill themselves on a train, they'll just go to the nearest bridge.

That's not true. Method substitution takes years.