That means they would need to use new cones with transponders. Yes, it's more expensive, but also way more reliable.
I used to do QA for the Waymo cars, and boy do they get worked into a tizzy if there's any kind of construction going on. It was the most common situation for remote assistance (read: people sitting in a room sending pathfinding suggestions) to get involved.
Judging from some of these comments, the problem is still very difficult.
(Seriously, cones really ought to be dealt with by image recognition? Easiest possible case, an object specifically designed to be seen?)
Another press of the button dispenses a martini.