It was set up in my opinion to make the work easier for the jdubs...
With respect , the Society never has an aim to make it "easier for the brothers". Their opinion is generally that most rank & file JWs are slackers and should work harder - hence the constant direction to "exert yourself vigorously" etc.
My impression is that many of the ex-JW posters assume that the GB has a strong degree of introspection and self analysis that simply doesn't exist in reality ( a point Ray Franz's books makes very clear. )
My take on the cart witnessing was that this was a brainchild of a GB member , started in New York and although the tangible results were negligible , it gave a good impression of activity to see JWs outside train stations & in high footfall traffic areas , so the GB decided to run with it.
Although 1.4% growth isn't great , it is still a lot better than many religions. To have even zero growth in Europe , for example , is to beat the trend of most of the established religions. The only ones in the UK showing any growth are "happy clappy" types or those using social / welfare type methods to get converts. I watched a program recently on born again Christians setting up a debt charity as a means of getting people to church https://www.bbc.co.uk/programmes/b0bmblny and the Trussell Trust https://www.trusselltrust.org/about/mission-and-values/ which runs food banks in the UK is basically a Christian front organisation.