How often do cars backfire? The internet is telling me that fuel injection and computer controlled mixtures have made it rare in modern vehicles. Carburetors were largely gone from new cars by around 1990.
Construction sounds might be a more common issue. Lots of nail guns use cartridge loads, for example. Or fireworks. Or impact hammers like you would use in a muffler shop, street jackhammers, etc.
It's relatively uncommon nowadays compared to the number of cars that don't backfire. But I certainly hear cars backfiring more frequently than I hear gunshots.
And then some hobbyist decides that backfiring is really cool, and tunes their vehicle to get that effect.
It’s almost a daily occurrence around where I live in the San Francisco Outer Sunset suburbs.