I think you’re mistaken. Electron apps bundle a specific version of the browser with themselves (which often doesn’t match the user’s version), thus loading up to twice amount of libraries and all the dependencies. This increases memory usage. Also the linked benchmark shows Tauri uses significantly less memory than Electron. 540MB vs 270MB in best test cases.
370 not 270. In the other test it loses, so it's not really conclusive.
It's true you have to load up more code for electron, but not everything in the chrome package is code and lots of it gets mmapped anyway. A large part of the memory usage for the electron/Tauri apps is the chrome heap and loaded app resources - that doesn't get deduplicated. An empty chrome (just started with no tabs or extensions) uses 350MB of RSS memory for me. That's going to be slightly lower for electron, but that value will be the lower bound for every single electron process started.