How many installations SQLite has is not that relevant in a discussion of SQLite vs full RDMS. By your example, a bank should use SQLite because it is deployed

How many installations SQLite has is not that relevant in a discussion of SQLite vs full RDMS. By your example, a bank should use SQLite because it is deployed widely. You have to look where they are deployed and the use cases. They also come with dramatically different tooling which make sa huge difference. More tooling does not mean that a full RDMS is a better choice: It is just about what you need, what use case you need to cover and what industry you are in.