Although without a source, the same wikipedia article is claiming there have been some controversy (and possibly some legalization) around the 19 mm banana spacing and European sockets:
"In most European countries, the standard mains power receptacle will physically accept banana and even US-style "double banana" plugs (the standard US pin spacing of 3⁄4 inch (19 mm) is close enough to the mains plug spacing of about 19 mm, and the pin diameter is also compatible), leading to a risk of electrical shock. For this reason, throughout the European Union, audio amplifiers and loudspeakers that accept banana plugs must have plastic plugs in their sockets which can be manually removed by the user.[citation needed] The UK was included in the prohibition even though such mains sockets were not used there.[citation needed]"
That might be one reason why more and more the safety type banana is preferred especially in Europe.