The International Civil Aviation Organization (ICAO) Standards and Recommended Practices have the following requirements:
...that landplanes be equipped with either one life jacket or equivalent individual flotation device for each person on board:
a) when flying over water and at a distance of more than 93 km (50 NM) away from the shore;
b) when flying en route over water beyond gliding distance from the shore, in the case of all other landplanes; and
c) when taking off or landing at an aerodrome where, in the opinion of the State of the Operator, the take-off or approach path is so disposed over water that in the event of a mishap there would be a likelihood of a ditching.
So, it would appear that the option of providing either a life jacket or an individual flotation device is an international standard.