TDD encourages the use of mocks and unit testing to increase code coverage. And unit testing is specially dangerous. You write a test, then program, so the test is helping you (the programmer). Selling the idea that the higher the test code coverage is the better and safer your code is. Not true at all. If your code doesn't have integration tests for example, you will never know how it actually runs. If you mock everything, you are not really "testing" anything but your internal logic. Unit testing and code coverage just checks that a code path has been run. But there are other tools like fuzzy testing or mutation testing... Do you randomize the memory at every test run? Do you make sure that the CPU cache is cold or hot depending on the test? Good testing is hard.
Most unit tests are written to ease the development. After finishing the development, they are safe to delete. Because they don't add any real value as I understand it. I understand that a test is a business contract of something that MUST work in a certain way. Unless the contract changes, the test must never be removed or changed. TDD and exhaustive unit testing make the maintenance process harder because you don't know if a test is useful or not.
If you follow TDD, most unit tests are re-written all the time. Because they were not written to test a business or critical contract, they were originally written to help some programmer write some internal logic.