Do other countries have a oral exam system similar to French “colles”?
The correct answer to this question is either yes or no. To answer yes one would simply need to provide a single example of another country with an oral exam system similar to the French system. To answer no we would need confirmation that no other country uses a similar system. To start the alphabetical list:


United Kingdom: Undergraduate students at the top universities tend to begin their studies immediately following their A-Level examinations which do not have a substantial oral component.  
United States of America: Undergraduate students at the top universities tend to begin their studies immediately following their high school/secondary education. Admission is based upon performance throughout high school and standardize test neither of which have a substantial oral component.