Why are there trees along country roads in France? Aren't they dangerous?

One of my fondest memories of France are the country roads lined with stately rows of plane trees.  While some believe that it was Napoleon who first planted these trees in order to shade his marching armies from the sun, the trees were already a feature of France before Napoleon’s time. Noblemen planted the trees to beautify the public roads leading to their estates.

The huge trees seem dangerous because if you lose control of your car, instead of careening into a field you will smash into a tree.  The statistics show that nearly one in 10 of the road deaths in France are from hitting trees.  Apparently some regions have begun cutting down the trees along busy stretches of road but it hasn’t made much difference. Cars are still spinning off the road but crashing into other objects instead.