It depends. In general, a plumber would be more likely to install a dishwasher because it is a plumbing fixture. However, there are some dishwashers that do not require any plumbing, so an electrician could install it.

It depends on the dishwasher. Some dishwashers have a simple electrical connection and can be plugged into an outlet like any other appliance. Other dishwashers require a water supply line and drainage hose, so they would need to be installed by a plumber. Still others have both an electrical connection and a water supply line/drainage hose, so either a plumber or electrician could install them.