A double square of this kind appears in appliances that were designed to isolate voltage sources so theoretically an electric shock is not possible. The insulation may appear in multiple forms to achieve this goal, normally using non-conductive materials like plastics.
If the appliance doesn't derive voltage where the user touches after a normal use, there's no possibility of danger after a fault and then a three prong plug with earth is not necessary. This is the standard for very usual electric devices like chargers or other types of AC/DC converters with a male plug that only has two-prongs.
In a world where the electricity continues being pretty new, or even non existent in multiple places, numerous appliances do not comply with security standards nor have the necessary information on them. It exposes users to an unwanted risk with possible fatal consequences.
A good reason to buy products that need electricity to operate from locations with regulations on the matter, and never trust unknown sources with low price and apparent low quality. Any user should inspect every appliance, and also that the building has a system that stops the electricity in case of a short circuit. Some call it a dead short. It could start a fire as well creating property damage or worse.