Yes, we are talking past each other. I never claimed a bad lane change is probable cause for a search. But searches are not the only thing the fourth amendment is supposed to protect against.

I don't think talking about roadside detention is moving the goal posts at all -- it's an abrogation of the fourth amendment allowed within 100 miles of the border, and has knock-on effects that make searching easier.

I agree that the way the ACLU characterizes the rulings are wrong, and said as much in a parenthetical. But that's not the same as "thus we shouldn't be worried about the fourth amendment being ignored within 100 miles of the border".