The narrower single lane bridges tend to force some moments of cooperation. Yes there are some moments of turbulence in which opposing drivers tussle over right of way, but most of the time people are polite and are moved to a wave of thanks to each other in letting each other pass.
The two lane road allows for a more seamless passage of opposing traffic to be sure, cutting down on social friction. But with a seamless and frictionless passageway comes a fading of contact with the other.
