Outdoor electrical outlet models are incredibly useful for those who need easy access electricity to their garden for a lot of the time.
In countries where the temperature regularly drops below 0 degrees Celsius in the winter there's not often a big need of them. This is generally because the summers aren't themselves particularly warm, and so the garden is not actually used a great deal. In other countries however, which have either much warmer summers or have in general a much warmer climate then there's a much greater need of them. If you take a look at the United Kingdom for example, which rarely has summers that have more than a few hot days there's not a big need of outdoor electrical sockets. But as soon as you take a look at a country like Australia, which is practically always hot and sunny it becomes a very different matter because their gardens are used a lot more, and so outdoor electrical appliances such as electric barbeques are utilized on a much larger scale.
Installing an outdoor electrical outlet is a simple enough job for a trained electrician, but complex enough so that your average handymen (or yourself) probably don't have the expertise to install one properly. Firstly a hole must be made in an outer wall, and wires must be put in connecting the mains electricity to it. From here an electrical box must be properly installed and then connected to the main electricity all using the correct safety protocols to stop electrocution.