The U.S. visa waiver system, like the proposed European model, was introduced after terrorist attacks within the borders of the United States, specifically after the attacks on the Twin Towers in September 2001. The fact that so many people these days are comfortable with the Internet also makes online immigration applications much easier. The U.S. ESTA is only used for people who come from selected countries which are deemed ‘lower risk’. This means that if you are a national of Holland or Japan, for instance, you can apply for an ESTA in advance of travel to the U.S. If you are a national of Sudan or Iran, you need a full visa.
The ESTA still allows a degree of monitoring over who is allowed into the U.S. but cuts down the bureaucracy involved in full visa applications. ESTA holders are currently allowed 90 days maximum at a time in the U.S. on a bona fide trip. If visitors wish to stay for longer, they still have to apply for a full visa.
In 2016, Canada also launched a similar visa waiver system to the ESTA called the eTA.