Why do drivers not slow down when they see signs indicating road work? I found the following anecdote on Quora

Many years ago, I worked for a gas &amp; electric power company, and had
been a member of a crew installing a road-side gas main. Despite the
signs, flashing lights, and traffic cones we'd set up well in advance
of the work zone, the overwhelming majority of people would speed past
us--sometimes within an arm's length, seemingly having no regard for
our safety. Our supervisor showed up to check on our progress, and,
witnessing the danger, he walked to our truck, took out a yellow
compressor hose, and rolled it out across the road. Immediately &amp;
without exception, from that point on, every single car slowed down
before driving over the hose.

This is the worker's interpretation of the behavior:

In my youthful mind, I concluded that people were simply more
concerned about damaging their cars than they were about damaging
other people, but in my now middle-aged mind, I believe it's more
complex than that. Maybe it's one of those countless subconscious,
split-second decisions our minds have to make throughout each day,
assessing probabilities &amp; adjusting accordingly: 'I see the road crew,
I've never struck a person with my car before, it's much more likely
than not that I won't strike a person today, and those people are
aware of my car &amp; have the ability to avoid it, therefore, carry on.'
[versus] 'I see an object on the road, I see that I can't avoid the
object, I've experienced damage to my car before when driving over
objects in the road, and that object isn't going to move, therefore,
caution is merited.'

Is this interpretation correct?
Presumably the decision of drivers to slow down in response to work zone signage is influenced by many factors.


Signage and road factors: Presumably there are a wide range of factors related to the nature of the signs and the structure of the road setting that influence whether people slow down. For example, I've seen road work signage on freeways that were often in place even when no actual road work is occurring. In these cases I've seen many drivers slow down little if at all. In contrast, I typically see much greater reduction in speeds when actual road work is occurring. Or for example, I imagine that a worker standing with a sign would be more effective than a static sign.
Cultural and norm factors: Presumably countries and regions  differ in cultural attitudes to driving, the acceptability of speeding, and the general tolerance for risk taking. Road safety advertising employ a wide range of strategies for reducing speeding including targeting personal interest (e.g., you'll get fined if you speed) or highlighting consequences (e.g., speeding increases the likelihood of killing yourself and others). 


A few empirical studies

Jarvis (1983) performed empirical research on Australian highways and found that 


  There is a clear indication that work area speed limits reduce vehicle speed on entry into the work zone; however, the large majority of drivers still exceed the speed limit posted. 


Garber and Patel (1995) found that signs triggered by radars indicating excessive speed were more effective in slowing cars than static signs.

References


Garber, N. J., &amp; Patel, S. T. (1995). Control of vehicle speeds in temporary traffic control zones (work zones) using changeable message signs with radar. Transportation Research Record, (1509), 73-81.
Jarvis, J. R. (1983). The Effectiveness of Road Work Speed Limit Signs. Australian Road Research, 13(3).