The USSC would disagree with you that any rights are truly lost. Read Michigan Dept. of State Police v. Sitz, 496 U.S. 444 (1990). Among others.
That has not been my experience, but if that's the case in your city perhaps someone needs to bring it up. The rules are rather simple.
Being allowed to avoid the checkpoint does not work in the real world because many police do not respect the rules.
Here in CA where we live, here are the rules:
In Ingersoll (1987) 43 Cal.3d 1321, the California Supreme Court established guidelines for what it would consider to be lawful sobriety checkpoints. The eight "functional guidelines" provide guidance for departments and the courts in evaluating sobriety checkpoints:
(1) Supervisory-Level Decisions. "The decision to establish a sobriety checkpoint, the selection of the site and the procedures for the checkpoint operation should be made and established by supervisory law enforcement personnel, and not by an officer in the field."
(2) Neutral Formula. "[A] neutral formula such as every driver or every third, fifth or tenth driver should be employed."
(3) Safety Precautions. "Proper lighting, warning signs and signals, and clearly identifiable official vehicles and personnel are necessary to minimize the risk of danger to motorists and police" and the "checkpoint should be operated only when traffic volume allows the operation to be conducted safely." The court noted that screening procedures may be altered depending on volume.
(4) Reasonable Location. "The location of checkpoints should be determined by policy-making officials rather than by officers in the field" with safety factors "considered in choosing an appropriate location" and the sites chosen being the "most effective in achieving the governmental interest; i.e., on roads having a high incidence of alcohol related accidents and/or arrests."
(5) Time and Duration. "[L]aw enforcement officials will be expected to exercise good judgment in setting times and durations, with an eye to effectiveness of the operation, and with the safety of motorists a coordinate consideration."
(6) Indicia of Roadblock. "The roadblock should be established with high visibility, including warning signs, flashing lights, adequate lighting, police vehicles and the presence of uniformed officers" for safety reasons and because "advance warning will reassure motorists that the stop is duly authorized."
(7) Length and Nature of Detention. "Minimizing the average time each motorist is detained is critical both to reducing the intrusiveness of the stop on the individual driver and to maintaining safety by avoiding traffic tie-ups." The court noted that drivers displaying signs of intoxication could then be directed to a separate area for a roadside sobriety test.
(8) Advanced Publicity. "Publicity both reduces the intrusiveness of the stop and increases the deterrent effect of the roadblock." Note, however, that a sobriety checkpoint that complies with the rest of the Ingersoll guidelines but is not preceded by advance publicity is not invalid under the Fourth Amendment. (Banks (1993) 6 Cal.4th 926, 931, 949.)
When a checkpoint stop is challenged, the People must introduce sufficient evidence to establish the legitimacy of the checkpoint. (Alvarado (2011) 193 Cal.App.4th Supp. 13.)
Note that it does NOT say that detour signs and routes need be indicated before you get to the location only that there be "advanced publicity" and that there be "indicia of [the] roadblock."
Which of these have you seen violated, and what have you done about it? Notify the media? Notify the local law enforcement agency in charge? Speak to city officials? And if the program is funded by an OTS grant, perhaps you can speak to the OTS.
Are they making these stops without reasonable suspicion or probable cause? All because an officer follows and stops someone does not mean the stop is unlawful.
In my town the "roving patrols" go after everyone who chooses to turn before the stop.
Where I used to work in So Cal we used to set up the warning signs in an area where there was a dual set of double yellow lines (forming an "island" in the middle of the road). You could turn right onto the obvious side street, or flip a U-Turn over the island and commit a Vehicle Code violation. We would position a car to watch for the U-turn. Oddly enough almost every vehicle that ever flipped a U-Turn had an impaired driver! Had they just gone to the right, they would have been fine.
All because there are cars set to investigate drivers that might deviate at the indicia of the checkpoint does not mean anything unlawful was done.