I only used wp once but the most surprising thing for me was that default installation used 7 SQL tables and their schema uses 3 different conventions (table.ID

I only used wp once but the most surprising thing for me was that default installation used 7 SQL tables and their schema uses 3 different conventions (table.ID/table.table_id and table.foo/table.table_foo). Maybe if DB themselves enforced some kind of limits like [a-z0-9_] this would never happen.