4 cases of treating the symptoms
Lately I have been thinking about various problems for which the "simple, direct solution" had negative effects. In particular, a problem that China is currently experiencing (warning: unsubstantiated claims ahead): city traffic. China's traffic problem is very serious right now and the government understands that fact. Unfortunately, their solutions have been too direct--i.e. completely ignored the underlying cause of the problems. Too many cars on the road?
Solution: make it illegal to drive cars with certain license plate numbers on certain days. This has had the unfortunate and rather ironic side effect of encouraging people to buy multiple cars in order to circumvent the block. (Many car buyers in China are exceedingly rich, and own a car more for displaying social status than for transportation.)
Solution: make it harder to buy a car by having a lottery for car-purchasing rights. Now people who didn't even particularly want to buy a car before enter the lottery because they don't want to lose their chance to buy a car forever (or for a long time). Net result: more people wanting to buy cars, and a higher social status & desirability for people who own them (one of the reasons for the explosion of car-ownership in China, as mentioned above).
These solutions try to impose a certain result without understanding the underlying social structures that have contributed to the undesirable result. This is, of course, not limited to China; Western countries make the same kinds of mistakes. Most notably: want to introduce the deprived citizens of the Middle East to democracy? Depose the dictator by force and institute a democratic government. Simply forcing a democratic government on a people, interestingly, doesn't necessarily give them a democratic government.
A final example from Stanford. In front of the entrance to the Gates CS building is a wide sidewalk. Many students using this entrance park their bikes on the sidewalk nearby, ignoring the farther-away bike racks (which don't have enough capacity for the volume of students to Gates anyways). Stanford would like students to park in bike racks rather than on the sidewalk. Solution: they have an official-looking person come by every day and tag bikes with a "this is illegal, move your bike or we will impound it" sign. Obviously this doesn't do anything to improve the bike parking situation, and is blatant symptom-treating without any attempt to remedy the underlying cause (not enough bike parking in useful places).
(Note on unsubstantiated claims on traffic in China: from anecdotal reports I feel good about claiming the above, but as this is China, true results of government policies are hard to dig up.)