Here's why:
* Figurative Meaning: The phrase doesn't literally mean that being safe is always better than being sorry. It means that it's wiser to take precautions and avoid risks, even if it means being a little cautious or missing out on something, than to potentially face negative consequences.
* Fixed Expression: The phrase is used as a complete, established expression, and its meaning cannot be understood by simply examining the individual words.
* Common Usage: The idiom is widely recognized and used in everyday language.
Let me know if you'd like to know more about idioms!