schema.org/URL is one of data types defined for linked data. I hate it, because it is totally useless. “Hey, what is the data type of this attribute?” “URL.” That is nonsense.
An URL is just an identifier. That is URL, I know. Almost every thing on the web have an URL that denotes it. What I want to know is the data type of the thing that the URL stands for.
URL should not the subtype of schema.org/Text. The URL specified for a property as hyperlink should be interpreted as the location that the thing is. Not be the URL itself the thing.