But if you're going to run off the left side of the road, isn't it better to run into a stationary central pier, instead of oncoming traffic?
Excuse the long-winded digression, but I found this to be a surprisingly intriguing question, one in which the answer isn't very clear-cut—at least in terms of this 1940 example. Certainly if you're the innocent motorist who’s on the correct side of the road, you would rather the errant car be stopped by a pier or anything else—leaving you unscathed, regardless of the cost to the other guy.
Now if you are that other guy, I’m not sure which collision would be preferable. Sure, the pier isn’t hurtling toward you at 70, but it’s essentially unforgiving, thus redirecting all of the crash energy back to you rather than deforming itself. It’s also narrower than most vehicles and will potentially concentrate the destructive energy in a smaller area. Of course much of the outcome would depend on the specifics of the collision.
But I think the bigger issue with the dilemma you pose (strike pier vs. oncoming car) is that it tends to assume that the two outcomes are equally likely. Let’s assume you’re on a trajectory that will take you into the median under an overpass—and possibly into the left lane of opposing traffic. I’m visualizing the scenario as a sort of “spaghetti plot” with all possible paths drawn on it:

(Of course there are many more possible paths, but this should give you an idea.)
If there’s a center support under the overpass, that’s the end: There’s a 100% chance that you’re going to collide with the pier—and likely injured severely or killed. All of the scenarios in which you recover your vehicle and return to the correct lane are now taken away from you.
But let’s assume the worst and say that you haven’t recovered your vehicle in the median, so now you’re in the left lane of opposing traffic. There are still a few more things that have to go wrong before you have a catastrophic head-on collision. There has to be a vehicle in the opposing left lane in the same place and at the same time as you, the driver of that vehicle must fail to take evasive action to avoid hitting you, and you have to fail to take evasive action to avoid hitting it. Certainly, all of those things
can happen, but I tend to conclude that they’re much less likely than the very severe outcome of a single vehicle striking the support.
Of course this could all be avoided with a wider median and/or a continuous central barrier, which is the path the PA Turnpike Commission has taken on reconstruction and expansion projects since the ’60s.