For production setups, you usually want high-availability. So unless you use it on a network file system like EFS (which the SQLite author recommends against), SQLite is not an option.
But it just so happens that I’ve seen in the real world so many single instances of Oracle, PostgreSQL, Maria/MySQL, SQL Server etc. that I know in practice there is a big difference between what someone needs/wants and what someone gets.
A lot of that has also to do with the complexity of setting up HA instances of such databases. Also this is simpler with HA sqlite setups.