For tourists, most countries accept the licences issued by other countries without problems.
For residents, the usual rule is that you need to get a local licence after a few months. In some cases it's a simple formal procedure, in other cases you need to take a course and/or test.
The so-called International Driving Permit (IDP) is not a scam per se, it's simply a translation to a standardised format defined in an international treaty. It doesn't have any magical powers, it's just to make sure that everyone understands your licence (which could be difficult otherwise if it's written in Arabic or Chinese, for instance).
Note that many countries have dedicated ID cards, so the driving licence isn't considered "the" ID as it is in the US.