Eeeh, this particular bug was a race when applying WAL to the data files in a checkpoint. Postgres’s checkpointing is theoretically just as vulnerable to this class of bugs as SQLite, though it doesn’t seem to have equivalent issues today.
Online backups/replicas are nice until you’re charged for network traffic or have to recreate the replica from scratch, at which point the initial-restore-then-hook-up-the-WAL-stream dance is prone to all sorts of racy issues. If you’re lucky enough to have only a single process talking to the DB, SQLite seems like a nice way to sidestep that complexity while keeping a simple backup story.
Heck, this is basically the Redis model: a single process/thread coordinates all access to the data, and occasionally forks off a background job to snapshot the state somewhere. From that perspective, the Tailscale controller binary is a database; SQLite is just the data file format.