You don't have to pump any water in conventional locks - you rely on having a source of water (lake) higher than the top lock.
The wheel is quicker than a series of locks (not important for leisure use) more expensive to build but it's probably cheaper to maintain than 20 locks.
Probably not for most people. Might be useful for receptionists in a public area.
Useful if you can make it a requirement for eg. nurses stations in a hospital.
Postgress has certain features because it is competing, both technically and in marketing check-boxes, with other SQL databases. CouchDB is not an SQL DB (and not even an RDMS) and so doesn't automatically have to have the same rich set of features.
>The reason PostgreSQL et al have those features is because people want them.
The reason those features are in PostgresSQL is because they are in SQLserver, ... because they are in Oracle, ... because they are in DB2.
Based on that logic C should have had a report generator and the unix filesystem should have records - and your car would have a saddle and whip holder.
The wheel is quicker than a series of locks (not important for leisure use) more expensive to build but it's probably cheaper to maintain than 20 locks.