Times are bad, and some doctors are feeling the pinch and desperate; giving only 2 days worth of antibiotics so that you'll need to visit him again for more, so that you'll have to pay again for the subsequent visits. This is highly dangerous. What if the patient don't come back? The doctor without realizing it would have created a strain of virus resistant to the drug.
Also, watch out for doctors who insists you take medical tests that's totally not needed. If you have a gut feeling it's not needed, get a second opinion. If it's not life threatening the tests can wait a day or two.
If you come across doctors like these, it's time to change to a more ethical one.