Here in Vancouver, Parking By-law 6059 requires grocery stores to provide

…one additional space for each additional 20 square metres of gross floor area up to 2300 square metres

each of which must be

a minimum of 5.5 m in length and 2.5 m in width.

Put another way, the law requires a 14m² parking space for every 20m² of supermarket floor space.

Adding the necessary lanes to allow cars to get in and out, this law practically guarantees that grocery stores will be more parking lot than store.