You're trying to excuse the obfuscation and confusion that the signs create by the fact that the restrictions are motivated by a few different needs. But the government exists to serve the people. If the city wants to collect citations, it needs to make the signs understandable.

I also don't buy your cost argument. In all my life, looking at thousands of city blocks where I live, I've never seen parking rules change unless the street is being torn up and rebuilt and all the signs are being changed anyway.