I believe most of it is uneducated perception and the reason why SUVs are so popular is the apparent sense of invincibility. This article considers a couple of extremes, the Mini and an F-150, not hitting each other but both hitting a solid object at the same speed. The result is horrifying.
bridger.us » Archive » Crash Testing: MINI Cooper vs Ford F150
Here's another comparison, the Smart vs the Mercedes S-class.
Video: Mercedes S-Class vs. Smart
The smart holds together surprisingly well against the big Merc - known as one of the safest cars around. People's ignorance again surfaces with comments about the amount of damage suffered by the Mercedes as if the safest car would show the least damage! Volvo introduced crumple zones in the 70's but obviously have failed to educate many on their benefits and the essential part they play in occupant protection.