As you can see from the article, the cars make it difficult to get inside and try to find survivors. They're clogging up the entrance. That's specific to cars.
Imagine if they had good bicycle corridors instead. Most of the bikes would have been washed away, whatever is left is easier to move. Now you have a lane that was cleared fast and can be used by emergency service vehicles. The cars would take days to move and there might people trapped inside or between them.