Still the reality of this is that the spirit of the 4th amendment is that US Citizens are not to be stopped without probable cause and searched without a warrant period when going about their day to day lives inside their own country. Entering the country is something completely different which is why border searches (all kinds) belong at the border and other points of entry and no where else.

I think you’re misunderstanding the Fourth Amendment issues at checkpoints. The Court says this:

While the need to make routine checkpoint stops is great, the consequent intrusion on Fourth Amendment interests is quite limited. The stop does intrude to a limited extent on motorists’ right to ?free passage without interruption,? *558 Carroll v. United States, 267 U.S. 132, 154, 45 S.Ct. 280, 285, 69 L.Ed. 543 (1925), and arguably on their right to personal security. But it involves only a brief detention of travelers during which? ?(a)ll that is required of the vehicle’s occupants is a response to a brief question or two and possibly the production of a document evidencing a right to be in the United States.? ? United States v. Brignoni-Ponce, supra, 422 U.S., at 880, 95 S.Ct., at 2579.

Neither the vehicle nor its occupants are searched, and visual inspection of the vehicle is limited to what can be seen without a search. This objective intrusion the stop itself, the questioning, and the visual inspection also existed in roving-patrol stops. But we view checkpoint stops in a different light because the subjective intrusion the generating of concern or even fright on the part of lawful travelers is appreciably less in the case of a checkpoint stop. In Ortiz, we noted:

?(T)he circumstances surrounding a checkpoint stop and search are far less intrusive than those attending a roving-patrol stop. Roving patrols often operate at night on seldom-traveled roads, and their approach may frighten motorists. At traffic checkpoints the motorist can see that other vehicles are being stopped, he can see visible signs of the officers’ authority, and he is much less likely to be frightened or annoyed by the intrusion.? 422 U.S., at 894-895, 95 S.Ct., at 2587.

In Brignoni-Ponce, we recognized that Fourth Amendment analysis in this context also must take into account the overall degree of interference with legitimate traffic. 422 U.S., at 882-883, 95 S.Ct., at 2580-2581. We concluded there that random roving-patrol stops could not be tolerated because they ?would subject the residents of . . . (border) areas to *559 potentially unlimited interference with their use of the highways, solely at the discretion of Border Patrol officers. . . . (They) could stop motorists at random for questioning, day or night, anywhere within 100 air miles of the 2,000-mile border, on a city street, a busy highway, or a desert road . . ..? Ibid. There also was a grave danger that such unreviewable discretion would be abused by some officers in the field. Ibid.3

Routine checkpoint stops do not intrude similarly on the motoring public. First, the potential interference with legitimate traffic is minimal. Motorists using these highways are not taken by surprise as they know, or may obtain knowledge of, the location of the checkpoints and will not be stopped elsewhere. Second, checkpoint operations both appear to and actually involve less discretionary enforcement activity. The regularized manner in which established checkpoints are operated is visible evidence, reassuring to law-abiding motorists, that the stops are duly authorized and believed to serve the public interest. The location of a fixed checkpoint is not chosen by officers in the field, but by officials responsible for making overall decisions as to the most effective allocation of limited enforcement resources. We may assume that such officials will be unlikely to locate a checkpoint where it bears arbitrarily or oppressively on motorists as a class. And since field officers may stop only those cars passing the checkpoint, there is less room for abusive or harassing stops of individuals than there was in the case of roving-patrol stops. Moreover, a claim that a particular **3084 exercise of discretion in locating or operating a checkpoint is unreasonable is subject to post-stop judicial review.13

United States v. Martinez-Fuerte, 428 U.S. 543, 557-59 (1976)