They do it because self-appointed urban design "experts" go on internet sites like this and complain complain complain complain complain about how ugly and unbearable life is if they have to look at a parking lot.
![Stick Out Tongue](https://pics3.city-data.com/forum/images/smilies/tongue.gif)
I've never understood why people pay money to go to a car show, but cannot bear to see cars in a parking lot. They both have expensive cars lined up in a row.
![Think](https://pics3.city-data.com/forum/images/smilies/think.gif)
And if you think about it, the cars in a parking lot are usually expensive, interesting to look at, and have more variety than what you can see at a typical car show. Hmmm... maybe this should go in the "can you explain this" thread.
At any rate, shopping plazas and office buildings try to add a little landscaping to "offset the ugliness of the cars" or sometimes to hide them altogether (in the case of hedges) and end up forgetting that hiding the cars makes it difficult to use the lot.