This question is made sevaral times.. As far as Turkey
goes, for the boat you want to charter you will need exactly the same certification
to use the same boat in yr country of origin; simple..
Most people tends to believe that these rules are depending on charter companies.. Not true, these are imposed by the insurance
companies. Unless the charter company takes the risks, he has to comply with what the insurance
company is asking.
Lastly, some countries (like France) has no certification to use small crafts inshore. Then, a simple proof of competence (past experience, etc) is sufficient.
I don't know other companies, but in our charter contract
it says that if the competence of the skipper
is deemed inadequate to handle the boat, we may deny to give the boat and request the hire of another skipper".
This has almost never happened but it's safer for us to ensure that the boat and crew is in good hands.