Welcome Tor1500 and great to hear your thoughts and observations.
Maybe this Cart witnessing has backfired on them. You could hardly call it witnessing in the first place. They made it out to be something of a privilege if you were chosen/allowed to do it.
Those that weren't asked are probably feeling deflated and look at door to door work with less enthusiasm. Those that have done the trolley work must be finding it so easy to stand there and say nothing, no confrontations and no rejections. It's easy work and when they can't do it and go door to door instead, they also must feel less enthusiastic about it.
I just thought about the thread title and the use of the word 'zeal'. How old fashioned and out of date is that? They are trying to catch up to the modern day and age but are stuck in the past, it must be so boring to many and especially the younger ones who can't relate to it at all.