In the US a 240v plug is a physically very different plug designed for running high wattage domestic appliances like a dryer, oven, or electric range. Most homes only have one of these installed in the location where that appliance is expected to be. They are typically rated at 30 amps and are actually two phases of 120v. It is certainly possible to make a smart outlet that can handle two phases and 30A, but it would be expensive, and have limited market.