I think Jennifer might have hit the nail on the head when she wrote "laws were designed for cars". I would add that the expectations placed on cyclists by drivers may not be consistent nor attainable. As in Canada more of my tax dollars will go to health care than roads, and preventable chronic illnesses will suck up an unfair proportion of that spending it seems important to me to defend bicycles.
Part of the problem comes from perspective -unnavegable hazards may not be apparent from a vehicle. They may not even be apparent to the cyclist until the last moment necessitating emergency maneuvers. Also, what is reasonable for one person on a particular bike is not for another, so comparing one rider's actions to another may not be fair. Like Vera you won't get much of a turn signal from me when I'm on a road bike descending and turning. The conditions of bike lanes can also vary wildly from one block to another so how can you make generalized laws?
Another factor that motorists often don't take into account is the toll exertion and weather can take. Sitting in a climate controlled vehicle with your foot on a gas pedal it can be tough to empathise with someone who has climbed a big hill, baked in the sun, frozen in wind chill or totally depleted their blood sugar - but it can have a huge effect on the reaction times and clarity of a person on a bike. Some empathy and neighborliness would be nice, but might be a tall order.
Personally I will continue to wear reflective fluorescent clothes, use blinky lights and even scream at the top of my lungs to let drivers know I am present. I will also sprint past smoke spewing tailpipes.