Even in the world of DWI enforcement the officer who makes a stop generally swears to the nature of unsafe driving or a moving infraction. I would be fine if the tipster could be made to testify to the nature of the unsafe driving. But anonymous for me is too much like having a baggie of drugs or a gun to drop near a suspect as evidence. The potential for abuse is absolutely enormous.
That they aren't looks like a possible violation of the sixth.
Amendment VI
In all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial, by an impartial jury of the State and district wherein the crime shall have been committed, which district shall have been previously ascertained by law, and to be informed of the nature and cause of the accusation; to be confronted with the witnesses against him; to have compulsory process for obtaining witnesses in his favor, and to have the Assistance of Counsel for his defence.
It’s the anonymous (thus unreliable) tip without corroboration that is the problem.
The cops can follow the car and pull it over if an independent lawful reason exists.
But to stop based solely on the tip is way out of line Constitutionally speaking.