Because there's little regulation of e-cigarette devices, manufacturers have leeway to market their products as cigarettes that can be smoked anywhere, presenting them as smokeless tobacco products that have no health risks. Because of that, e-cigs are allowed in otherwise smoke-free environments.
Regulations do vary, though. Some countries, including Australia, Canada, Israel and Mexico, as well as some U.S. cities like Los Angeles, Chicago and New York, have banned electronic cigarettes or restricted their use in some public venues. In some cases, use of e-cigs is allowed only in "vaping" lounges or stores where the devices and associated products are sold [source: Gorman].