You can clearly see the sign forbidding the left hand turn. You can clearly see the city hall clock so you know the sign is not mistaken. The parking checker blocked traffic heading north while he/she waited for the opportunity to make a left hand turn. The city which is so concerned about the flow of traffic (as if there is any - and you can clearly see that there isn't) forbids left hand turns. Unless you are a parking checker headed off to do his duty fighting the crime of parking.