obviously as we all know there is left and right hand drive. why can't in the world just have one side driver? same things apply to 110 volt and 220 volt. why can't they just make one voltage? any reason(s) behind these?
About a quarter of the world drives on the left, and the countries that do are mostly old British colonies.
This strange quirk perplexes the rest of the world; however, there is a perfectly good reason.
Up to the late 1700's, everybody travelled on the left side of the road because it's the sensible option for feudal, violent societies of mostly right-handed people.
Jousting knights with their lances under their right arm naturally passed on each other's right, and if you passed a stranger on the road you walked on the left to ensure that your protective sword arm was between yourself and him.
Revolutionary France, however, overturned this practice as part of its sweeping social rethink. A change was carried out all over continental Europe by Napoleon.The reason it changed under Napoleon was because he was left handed his armies had to march on the right so he could keep his sword arm between him and any opponent.
From then on, any part of the world which was at some time part of the British Empire was thus left hand and any part colonised by the French was right hand.
In America, the French colonised the southern states (Louisiana for instance) and the Canadian east coast (Quebec). The Dutch colonised New York (or New Amsterdam). The Spanish and Portugese colonised the southern Americas. So The British were a minority in shaping the 'traffic'.
The drive-on-the-right policy was adopted by the USA, which was anxious to cast off all remaining links with its British colonial past
Once America drove on the right, left-side driving was ultimately doomed. If you wanted a good reliable vehicle, you bought American, for a period they only manufactured right-hand-drive cars.
From then on many countries changed out of necessity.
Today, the EC would like Britain to fall into line with the rest of Europe, but this is no longer possible. It would cost billions of pounds to change everything round.
In 1967 Sweden changed from driving on the left to driving on the right. Everybody expected the number of deaths on Swedish roads to go up in the first months after the change, but the opposite happened: Fewer people died! Why? Because everybody was driving more carefully than they used to. Thus, changing side actually saved lives, rather than killing people.
As for the electricity, the best I could find was this: (how accurate? I haven't the faintest )
"U.S. power is suppleid to homes as two 110 volt alternating current feeds that are out of phase with each other. When a double pole breaker in your electrical panel is used to connect them, the result is that they add up to 220 volts because when one line is 110 volts " positive" the other is 110 volts "negative" resulting in a difference of 220 volts. European power however is single phase 220 volts. U.S. power is 220 volts two phase, or in many industrial applications it is three phase. Sometimes it is also supplied as two phases of a 240 volt 3 phase power supply which results in 208 volts. Other than that the european power is 50 cycle as opposed to 60 over here."