Storing cars is very expensive. The only thing more expensive is building parking spaces to store cars and then have them never be used. What a waste!
Can you imagine Wal-Mart building an entire row of their store and then leaving the shelves empty? It would be ridiculous. Why then do we simply accept that large swaths of their land would be built upon for a use (parking) that literally never happens? We accept it because that is the price of entry, the cost of complying with local regulations.