Something is not quite right here?

Allow me to explain. There have been guys in orange overalls with spray apparatus going around house to house in the neighbourhood, saying they need to spray in native or fruit tree for fruit flies. They said the trees only needed two sprays to be protected. This is the sixth time they have been around and the fourth time the same two fellas have done it.
At first I thought that they had not communicated with each other and gone behind another group and redid it by mistake. But now having seen the same two guys for the forth time, I'm not so sure.
And its also a worry that you could let someone into your backyard without a second thought if they have overalls and a spray gun.