Why is StringValues used for Request.Query values?

Let's say I have some url that looks like this: www.myhost.com/mypage?color=blue

In Asp.Net Core, I'd expect to get the color query parameter value by doing the following:

string color = Request.Query["color"];

But it turns out that the Request.Query["color"] returns a value of type StringValues rather than string. Why is that?

Apparently the StringValues type can hold an array of strings and includes support for implicit conversion to string[] which is cool but why is that needed for a query param value?

Having to get the value like this seems odd:

string color = Request.Query["color"].ToString();

And worse, checking for a value to see if a query param is specified can no longer be done like so

if(Request.Query["color"] == null) { 
      //param was not specified
  }

but instead must be checked like so

if(Request.Query["color"].Count == 0) { 
      //param was not specified
 }

Since a single query parameter can't have multiple values (as far as I know) why does Request.Query["color"] return a StringValues object rather than a string?