I served as a reserve police officer for 15 years. Sneer at me if you wish, but we performed a service to the community, and I do have a lot of road patrol experience. I never participated in a license check roadblock during that time, but was detained by one, and have been through a couple since. I felt it an infringement of my liberty, and at the time was late, made later by the stop. As for providing for the public safety, they suck IMO. If all the officers involved were on the road observing traffic, they would have collectively been able to observe far more vehicles and probably made as many or more arrests. Drunks even if not weaving, will do plenty to warrant attention on the road, whether driving agressively, slowly, no signals, improper lane usage or other violations. Yes, normal citizens do some minor infractions too, and should not be ticketed for BS stuff. I can only speak for the guys I worked with and the general attitude of road patrol folks I worked with, but most didn't want to write tickets except for egregious violations. However, when we stopped vehicles, even though we might have been trying to apprehend DUIs, there was a legitimate reason for a stop, the nature of which was a ticketable offense, or driving behavior indicating impairment. Drunks were arrested, others were usually happy to have a cheerful, "signal your turn next time, and have a good night", or some such, receiving a verbal warning instead of a moving violation. It was never a problem to make DUI arrests. Citizens going about their business without PC for stops were never inconvenienced. Those officers were looking to provide for removal of drunks, but did not infringe on anyone's rights.
IMO, an officer can easily find all the drunk drivers he has time to process with only a bit of an effort. Traffic blocks don't allow officers to arrest more drunks IMO, and are certainly an intentional infringement on the rights of drivers that warrant no detention for anything.
Those days seem long gone. It seems today that governments can find an excuse for whatever they want to do, and courts willing to allow it.