The idea behind compact parking spaces is that small cars can fit into smaller spaces and more spaces can fit into the parking lot. So by having these smaller spaces in addition to the big ones for everybody else, you should be able to fit more cars into the parking lot. And that's what everybody wants, right?
If you can designate a larger percent of the required spaces as "compact" you can provide more spaces in a smaller area and build a bigger building. A bigger building means more profit, higher density and more traffic. Most cities have building codes which limit the percentage of compact spaces in a lot but it the regulations may vary from 20 to 50 percent.
These spaces, however, are not policed. So the problem that arises is that everybody uses compact parking spaces -- not only people with larger sedans, but minivans and SUVs, or anything else that can be squeezed into the space. This natural result of this is car dings, scratches, and uncomfortable entry into one's vehicle.
Some people believe compact parking spaces to now be obsolete with the trend towards larger vehicles, and have attempted to ban the creation of future compact spaces in their cities. While this is unlikely to happen in the immediate future, it IS likely that there will be percentage decreases for compact spots.
Or perhaps we need to get out of our "bigger is better" mentality.
To the driver of the navy blue Nissan Pathfinder which was parked next to my Toyota Camry this morning, you are not driving a compact car. Then again, am I?