The whole idea is still really new. Some of the objections being brought up don't necessarily apply. Any building generates a lot of grey water and a drainage

The whole idea is still really new. Some of the objections being brought up don't necessarily apply. Any building generates a lot of grey water and a drainage issue. Keeping the water local, maybe using some simple treatment techniques, could control the runoff and also make use of it. Buildings usually have one side that gets a lot of sun. There are also many methods being used to advance daylighting including lenses and fiber optic lines. This has so far been expensive, but is competitive with powered lighting systems. Of course attempts to duplicate existing farms in cities will have issues. Many of these may be resolved. For example, even current farms are beginning to make use of automated weeding and picking machines. This could make it practical to grow in awkward built places that have limited or no safe access. It is also really important to bear in mind the ugly reality of massive farm failures. When volcanoes blot out the sky for a year or more, which happens every few hundred years, all currently dominant forms of farming fail absolutely and catastrophically. However, in such circumstances some vertical farming setups would have limited challenges. It may be difficult to efficiently and reasonably plan for such scenarios, but we know absolutely that they will happen and it has already been a while since the last really big volcanic event.