This article said it would pick people up downtown, but how far would they go to drop off? The golden triangle is mostly grid-based, but go elsewhere in the city and the road topology gets jacked up fast (like Boston), especially in the south and west. Its idiosyncrasies took some getting used to, after living in flatter regions with gridded streets for several years (central Ohio, Salt Lake). In those places, if you want to go somewhere, you start driving in its general direction; in Pittsburgh, it's not uncommon to go in the opposite direction for a while, since the roads don't connect that way.
The article also mentioned bridges being a problem. In Pittsburgh, that's a big problem, since it supposedly has more bridges than any other city in the world.