Why does Britain still drive on the left side of the road?

most other countries have made the switch to the right side. I saw a map recently and noticed that all of mainland Europe drives on the right. What gives Britain? Wouldn’t it be easier to have a universal standard for driving?
Yes, Peon. Point taken. Japan and India drive on the left as well. However, most countries that drive on the left were forced to by their British colonizers. Even Japan adopted the left-side policy with Gunboat Diplomcay instituted by the British in the 1850s. Still, less than a quarter of the world uses the left side of the road.