Comment by deinonychus

I haven't thought hard about this, but I think the solution relies on some definition of a 'platform' or a similar idea. I think most people could see a difference between the carsigns and the websongs, where the latter look like ads because they're on someone else's platform.

I think we can narrow down on weird cases in between the carsigns and the websongs. Maybe the line gets muddier if the employees aren't driving their own cars with signs, or if those employees are hired to do nothing but drive, or if they're not even employees and they're Uber drivers but for driving signs... To me, that last one sounds like a platform which exists for nothing but advertising.