I rarely see the trolleys these day ( our town banned them as our local council requires a permit to advertise on the street in this way & the congregation refused to pay up ) but I saw one (unmanned) recently at an airport , beside another similar trolley from a evangelical Christian group.
It was mainly filled with ( public ) WT & Awake magazines and never having seen any for a few years. I picked up a pair. They were embarrassingly thin both on content and in substance - literally a 5 minute flick through. The stand was full - either it had been recently replenished or ( more likely ) the magazines rarely get taken. All in all - it did seem a bit pointless and ineffective.