This example points out again why rear lights are often so much better than the minimalist reflectors that come with most bikes and even larger reflectors. In the dark in the rain, a blinky is much more likely to get noticed.
I am especially frustrated with the failure rate of several different rear lamps I've owned. Sometimes an intermittent connection in a rechargeable battery or cable (NiteRider) turns off my rear lamp during a ride. Sometimes rain enters the blinky housing and shorts it out. Sometimes a pothole bounce causes the cover to pop off and spill the batteries, or even snaps the plastic mount clean off.
I am increasingly inclined to go with two rear lamps, rather than just one, especially when in a dark rain. That is in addition to large rear reflectors, my current failsafe.
But in answer to the OP's question, whenever I find myself surprised by a low-visibility road user such as a pedestrian in the dark, I am reminded that I must take care to drive slowly enough to respond to such users and to pay especially close attention in low visibility conditions. Sure, I wish other users would maximize their visibility, but I do not imagine myself striking them when they are traveling lawfully; rather, I am concerned about what those "other drivers" might fail to do.
A driver on a four lane road at sunrise once pulled up to me at a signal and told me that I was hard to see, and that I needed to be careful. I thanked her for her concern but pointed out that she did see me and that it was her responsibility to drive within her sight distance and pay attention. I do try to avoid riding directly into a harsh sunrise or sunset, but I am still surprised at the number of drivers who do not slow down when visibility is compromised.