SQLite is much easier to just start working with. I can prototype all I want and it's my own private db. I can run it on my laptop. For Oracle I need to have to ration my usage of tablespace, servers, client installation: too much bureaucracy. The deployment environment does have access to Oracle I can piggyback on if I must. Installing other databases may be tricky, but SQLite is so hassle-free to turn out to be fine.

The database is not a huge part of this project, anyway. I was hoping not to have many issues with it (I still do).