Hot-water systems can be elaborate and complex, running from a boiler or commercial water heater throughout a building, or dirt simple.
Sometimes dirt simple is the better and cheaper solution. This was a case where a department store needed a cleanup sink with hot water in its cosmetics department. The solution was a two-gallon, under-the-sink electric heater. No pipes to run from a big heater, with attendant radiant heat losses or wait for hot water. Just a little bit of hot water when needed.
The brown device on the right is an expansion tank, installed to ensure that destructive thermal expansion doesn't occur.