Renting a car in a foreign country involves more moving parts than a domestic rental - insurance rules, license requirements, and driving conventions can all differ in ways that aren't obvious until you're standing at the counter.
Some countries require an International Driving Permit alongside your regular license, and this isn't something that can be sorted out on arrival - it needs to be obtained before the trip, usually through your home country's motoring association.
Credit card travel insurance and personal auto policies often have gaps or exclusions for international rentals that aren't obvious from a quick read. Confirming actual coverage before declining the rental company's own insurance avoids an expensive surprise if something happens.
Driving on the opposite side of the road, unfamiliar road signs, and different right-of-way rules all take real adjustment time. Renting a smaller, more maneuverable car for the first day or two, rather than the biggest available option, makes that adjustment considerably less stressful.