Why is an Entity Framework 5 TransactionScope transaction subject to the Machine.Config System.Transaction timeout?

Why is an Entity Framework 5 TransactionScope transaction subject to the
Machine.Config System.Transaction timeout?

As I understand TransactionScope transactions, a transaction may be be
elevated to the distributed transaction controller under certain
circumstances.
According to this question and this post there was an issue when using
Entity Framework and SQL Server 2005 where transactions would be elevated,
but it should not happen when using SQL Server 2008 or above.
I am using EF5 and SQL 2008 and my transaction was timing out after 10
minutes. I could extend this timeout only by changing the
System.Transaction timeout value in my machine config.
I thought that System.Transaction timeout was only the timeout value for
the DTC.
So my question: Would the System.Transaction timeout set the value for all
transactions, not just a distributed one, or is my transaction been
elevated?