The Reality of Tipping in America

Around the world, it does look like most countries do not have tipping. According to Esther Marshall, USA is tipping culture explained as a tourist's nightmare. While tipping for a meal in the customer in the UK, a standard rate is 10 to 12.5% in the USA service charge can be sold. So now you have tipping on top of taxing at like most places, including apparently convenience stores, which makes no sense to me.