I've seen JWs standing by their carts in my city. As others noted, the JWs' bodies are there, but their minds seem to be elsewhere. They don't approach others or make eye contact. Might be talking to each other or standing quietly.
It's certainly not an issue here that they can't approach people for legal reasons. Lots of other religious groups are out there enthusiastically trying to initiate conversations, carrying signs, passing out leaflets, preaching about hell using loudspeakers, driving around in vans plastered with signs and blaring some preacher. And with the myriad of street performers, those JWs would probably get lots more attention if they put out a tip jar and either stood really still like statues or did a drumming routine on their carts.
As the JWs are around here, they're completely ignorable. And since the vast majority of JWs I know would sooner leave the religion than go back to the type of theatrics that JWs used to do with street witnessing and sandwichboard campaigns, this is WT's solution. The GB is willing to dumb down the ministry so the dubs can fake it like this. And why fight it? The door-to-door preaching certainly isn't that productive, so just let them stand around and count their time.