I think that most things that use sqlite as some kind of bolted onto the side option that's not exhaustively tested under load are full of subtle bugs.

For example, simply reading from a sqlite database can crash with BUSY if there's another connection performing a write at the same time. There's a solution to this (WAL) mode, but it's not the default. Since this only appears under load involving writes, I guess that most sqlite backed web services are affected.

And then there's this bug I found where database queries can still fail BUSY, even in WAL mode, when under certain types of load. No response from the sqlite devs on this bug yet. http://thread.gmane.org/gmane.comp.db.sqlite.general/93116

OTOH, if a program requires me to admin a SQL database, speaking as a user, I won't use it. Full stop. :/