Tauri uses the system’s native web rendering engine instead of shipping Chromium with the whole app. As a result you get much smaller app bundles (like 10 MB for a complex app), better startup times and less RAM usage. The downside is that you need to do slightly more testing but the end result is worth it.

They could have at least used Tauri.

Or from a developing country. That’s why I asked for the context in which Proton is too expensive. Getting all the services separately, doing E2E encryption manually etc. is probably cheaper but less convenient.

By what metric? In comparison to which other product?

It’s a nice all-round solution for a lot of privacy focused services. For me it’s worth the money.