For San Francisco (the city in the screenshot and the only city that ever seems to matter when getting app-based startups), the rule is that parking at a broken

For San Francisco (the city in the screenshot and the only city that ever seems to matter when getting app-based startups), the rule is that parking at a broken meter is still very much valid. Same goes for where I live and everywhere I've lived and tried to park in multiple places in the U.S. I suspect this is half an enforcement problem (doesn't look good in the papers, "City Tows People Parked at Busted Meters") and part not denying use of a parking spot just because the one pay box is busted. Broken meters are one reason why cities in the U.S. are going to parking time window stickers and fewer pay boxes. As for things like faded curb paint and missing signs and so on, that's not an excuse the operator of the vehicle can use. Even if there's no red curb paint here, you're still not allowed to park within 30 feet of an intersection (on the direction-of-travel side) or 10 feet of a fireplug or 5 feet of a driveway. Those are all things you're expected to know by virtue of having a driver license. Now, being ticketed for being over-time on a free parking stretch that's limited to 2 hours when the sign has gone missing might be one thing, but the folks around here put up so many signs in so many places, I think a person would have a hard time making that stand up. Ultimately: if someone isn't sure and wants to not risk incurring the fine, he or she shouldn't leave a hunk of metal and plastic sitting on the public right-of-way.