If you look at comparably sized cars the Model 3 is about the same. It's roughly the same size and weight as a BMW 3 series. And they're both around the size and weight of the average new car.

It's small electric cars that typically weigh more, because making the car smaller isn't the main way to make the battery smaller; reducing the range is. So then nobody really makes a small full electric car with a short range, because that market is served by plug-in hybrids that solve the range problem with a gas engine while still allowing you to do a few dozen miles a day as an electric car.