Do the road designers cheap out?

• The few roundabouts a couple decades ago may have been ambiguous but every roundabout I’ve seen for many years is clearly marked on the approach so you can’t screw up the direction.
• I understand someone unfamiliar may stop unexpectedly or not understand how to exit, but how do they screw up the direction?
• Even changing lanes which used to be where people screwed up a lot, recent roundabouts are clearly marked what lane you should be in and the lane markers lead to the exit: how can people not understand signs saying this lane for this road?

If your road designers aren’t following these conventions, that may be a contributing factor