Minimum parking requirements are the single most destructive zoning law, IMHO. Many professional planners are now recommending that towns and cities remove them--or have maximum parking, instead. How do they harm towns:
1. Devalue land--especially commercial property
2. Smaller lots cannot be put to highest and best use
3. Make town centers much less walkable but pushing businesses further apart; minimum parking also tends to greatly increase traffic congestion
4. Discriminates against smaller businesses that may not be able to weasel their way around these rules the way large chain stores do
5. Storm water runnoff, chemicals, erosion, asphalt acts as a heat sink--hot water can run off of these huge lots, harming fish and wildlife
6. Huge, five acre parking lots are not a good use of commercial land.
7. Towns end up with less property tax revenue from their commercial centers--and fewer jobs. If a business finds that having too many employees will require the addition of spaces that he cannot put it, they will frequently cap the total number of employees at a low amount--resulting in a few lost jobs. Other businesses will just cut down on the number of seats or shrink the retail area to something just smaller than that which would require one parking spot too many.
8. Worst of all, businesses no longer have any incentive to share parking lots or work together to solve mutual problems.
9. Parking lots--especially large ones--cannot simply be landscaped; they do not look nice, and do not work well with any zone or sector.
The worst effect is on town centers, where old buildings can no longer meet these minimum parking requirements because there just isn't any space for them. Developers find that it's too difficult to bring about the political change necessary to reduce or eliminate parking requirements. Although they may be grandfathered in to their old use, once you try to change some of the floors or buildings to highest and best use, you've got real problems.
It's often easier for building owners to just walk away from these buildings and invest elsewhere. People wonder sometimes why these buildings don't get renovated--why their town center is becoming run down, but voters rarely make the connection.