How so? the MIT license allows you to do everything with the code. It doesn't allow to sue the author, but that's about it. Here it is: https://opensource.org/licenses/MIT
No, it's not clear, and I guess that's up to the courts to decide.
But in my (non-lawyer) opinion - if the reproduced code is substantial/unique enough to be deemed to be covered by the license, then it's also substantial/unique enough to be subject to that license requirement.
> The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
Not including the copyright information for the MIT-licensed code is a violation of the license.