Can you elaborate on this?
I was looking for a source on this but cannot find one at present. Basically outlets, like most everything else, is built for a use case. 240V outlets have a rather strong spring to ensure good contacts with the plug. These outlets are intended for use by appliances, such as a dryer, where the appliance is plugged in and then forgotten. Or are put in a shop or garage where perhaps a welder is connected all of the time, or is plugged in when needed. This is an occasional use.
But if you plug and unplug on say a daily basis, the springs loosen. This happens with all outlets, but in the case of a 240V outlet with strong springs, when they get loose some serious arcing can occur. This is especially a problem when cheap outlets have been installed.