UDOT advised us that signs were covered in areas where traffic patterns and or lane lines were being changed or subject to change. The signs are simply an advisory, same as the GVW weight restrictions, where some areas are posted, but other areas meet the statute that do not have posted signs.
I don’t know the rationale for all of the signage locations, covering, or anything like that, but agree it could be much more clear. I think a big part of it is due to the lane closures, which change from day to day or day to night. If think if the signs saying do not cross double white lines are uncovered, and lane shifts with barrels or temporary lane lines are placed due to construction, it could cause issues - that’s just speculation on my part though.
Troopers still have discretion as to what they pull over and don’t, so the absence of seeing someone pulled over doesn’t mean UHP doesn’t know - they do know, but they may be on SE shifts or assigned to a call, which is why they may take no action.
My info is a few years old from when I was a trooper, from UDOT briefings to UHP. It’s always possible it has changed, but current UHP troopers will know the law status - there are always UDOT briefings and advisories for construction zones and projects, as UHP is primary enforcement and works the majority of construction zone safety shifts.