Do you believe a successful Transport Manager from a low populated small country can be a successful Transport Manager in populated large country?

Yes, if you are a quick learner and ready to take on the responsibility of a bigger role. Previous experience in the industry will give you the confidence to try. You must be able to multitask

A very definite NO and as witnessed on numerous occasions in my experience of Transport & Logistics in over70 countries, they are totally inadequate due to their limitations and, in reality they are a liability to the company and by no means an asset; just imagine taking Mr. X from Country X (running in relative terms a large fleet of100 vehicles), then put Mr. X into Country Y and have him run5000 vehicles.......IT JUST DOESN'T WORK!

Yes for sure because  it is the problem of the system not the population or the distances