Most vegetables actually have beta carotene instead of actual Vitamin A. It's a safe version that your body only converts to Vitamin A as it needs it. Anything excess is excreted naturally. This is why vegetable sources of Vitamin A are preferred over meat sources like liver since those store the actual Vitamin A form.

Interesting side fact: This is also why polar bear liver is toxic to eat because of it's massive quantities of Vitamin A. A single liver can have as much as 9 million IU of Vitamin A and human toxicity is generally reached at 300,000 IU.

When it comes to daily values for vitamins in food, 100% refers to the minimum amount a "normal" human being needs to be optimally healthy, and nothing more. How much over the optimal amount becomes toxic varies widely from vitamin to vitamin, so the DV doesn't really say how much you have to go over the DV value before you start feeling ill effects.

For example, the 100% Daily Value for Vitamin A is 3,000 IU, while the amount needed for it to become toxic is about 300,000 (for a single use) or about 30,000 (if you're doing it every day for an extended period of time), which correspond to 10000% and 1000% of the daily value, respectively.

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