If you consult this extensive list of connection string syntax:
http://www.connectionstrings.com/[
^], you will notice, that most providers have more than one connection string syntax. And yes, you might find overlapping - altrough you are wrong:
SQL Server standard syntax is:
Server=myServerAddress;Database=myDataBase;User Id=myUsername;<br />
Password=myPassword;
MySQL Standard syntax is what you have posted:
Server=myServerAddress;Database=myDataBase;Uid=myUsername;Pwd=myPassword;
So these are not equal, just similar. But what if? Nothing. Not the connection string defines the provider. It is just a string defining parameters. It is up to the provider manufacturer's choice to define this syntax. Could those be harmonized? Yes, maybe. But who would do this?