Why do different countries use different type of power plug and sockets?

Each country has it's own standard for the AC power plugs and sockets. The reason for that are the adoption of the basic standards for voltage and frequency. For example there are two standards dominant in the market right now one being 220–240 volts at 50 Hz and second is 120 volts at a frequency of 60 Hz. There are also variation of these two but these two are the most commonly used,

Most of the countries in Asia follow the similar line of power plug standard. Some do differ in how they allow AC current and voltage level for the devices. And for that reason the inverters, sockets and plugs are designed accordingly. So you may find that AC plugs in India being different than in US. In case of US the current requirement are from 2.5 A to 15 A. So that also reflects in the sockets. There are however total 15 different types of AC power plugs and sockets standards out there. Countries that have the member of the same standard would have the same power plug and socket.

Why not single standard throughout the world? There is International Electrotechnical Commission and International Commission on the Rules for the Approval of Electrical Equipment (CEE). But not all countries comply to the standards set by them. That's because countries do not want to adopt to the standard chosen by others which they have to adopt to for everyday use. For example US often doesn't agree to the standards of another continent just to comply with other countries standards. Asia and Europe however do comply in order to maintain the uniformity of standards. This is more of subjective issue than any strong technical reason.

When electricity was first invented and was introduced into the use of domestic environment, it was mainly for the purpose of bringing light to eradicate darkness. With more advancement it became an alternative for heating and also for using appliances to save manual labour-saving, as a means of creating a connection to the supply for other things apart from glowing up a light, the necessity of socket was felt. In the decade of 1920s, the two-prong electric plug was introduced.

Simultaneously, few electricity companies started to operate with a split tariff system to lower the cost of electricity that paved way for low wattage appliances which could be connected to the socket of the light.

As the requirement for more secure establishments grew, three-stick outlets were created. The third stick on the outlet was an earth stick, which was viably associated with earth, this being at the same potential as the impartial supply line. The thought behind this was that, in case of a short out to earth, a breaker would blow, therefore it could separate the electric supply and a life could be saved.

Now the question why the world is presently stayed with minimum 15 unique styles of attachments and divider outlets is that, on account of numerous nations wanted to build up their very own fitting, rather than embracing the US standard because the wobbly American plugs with their uninsulated prongs have become obsolete and aren't that safe to use.

To begin with, it is indeed a baffling issue when you visit different nations. The world has over 12 different types of sockets and plugs in different parts.
All this has to do with the evolution that the generation and usage of electricity have experienced over the longer period of time. Initially, the voltage was limited to 110V. By the time it was identified that 240V meant more power, it was already late to switch to 240V. That is the story that unfolded in the US.
Meanwhile. a company in Germany thought of a voltage of 240V and frequency of 50Hz. That had more of monopolizing in the area. Each country went of developing its own plans and strategy and that was it. That should clearly explain why we have different plugs in different nations. Every country developed its own standard regardless of what is happening in other parts of the world.

Is there any hope to change it now? Well, no - there has been heavy investment in this arena. So we will need to struggle with different sets of those as you travel across the world.