It isn't, actually.

Contrary to what people seem to assume, putting up minor obstacles to prevent suicide has been scientifically proven to be effective at reducing suicides not only at that specific location, but in the general area (meaning people don't just find another way to do it).

Suicide is generally an irrational, often spontaneous act. Suicidal people are, in the vast majority of cases, not thinking clearly. Requiring someone to engage their brain enough to come up with another method of suicide often makes them also question whether they actually want to do it or not. Having a big open fall on the other hand, offers a quick, convenient escape that someone who is feeling overwhelmed or desperate might be tempted by, even if they wouldn't do it if they had to actually make a plan.

Empirical evidence suggests that restricting access to certain suicide methods is highly effective at preventing suicide, prompting the construction of physical barriers in many high-risk jumping locations. However, some have argued that these measures are too costly and only lead to method or location substitution.

Results clearly show that physical barriers are highly effective at preventing suicide by jumping with little to no method or location substitution occurring. Furthermore, their cost is far outweighed by the monetary benefits of averted suicides.

A related concept, requiring guns to be kept in nested containers where you have to open multiple layers has been shown to reduce road rage incidents. Every additional barrier provides a chance for you to remember yourself. And having an easy means of suicide around the house (such as a gun) increases suicide rates. People are not computers.

If you ask me (or the scientists who have studied this), any large drop like this ought to have nets, and people on the internet can whine all they want about it.

From the assumption that nets would only be installed as the result of a lawsuit and that the nets would cost the hospital money it doesn't have, when in fact they probably save the hospital money.