Here's why:
* Sign languages are distinct languages: Just like spoken languages, sign languages are unique to each region or country. There are hundreds of different sign languages worldwide.
* Sign languages are not based on spoken languages: They have their own grammar, syntax, and vocabulary. For example, American Sign Language (ASL) is very different from British Sign Language (BSL).
* Regional variations: Even within a country, there can be regional dialects of sign languages.
However, there are some similarities and influences between sign languages:
* Influence of spoken languages: Some sign languages may have borrowed signs or structures from the surrounding spoken languages.
* International sign: There is an International Sign language used at international events like the Deaflympics, but it's not a primary language for any Deaf community.
In summary: While sign language is a vital form of communication for the Deaf community worldwide, it's not a single, universal language. It's important to understand the diversity and uniqueness of different sign languages.