The whole point of the article is that in the past, we could not shop for cabs while hailing them, but the ability to do high-tech cell based hailing changes that, and lets us have a market again, and a market is, generally without exception, better.

Tourists can't shop as much -- this is a very common problem, and it's why tourists often pay vastly more than locals for all manner of products and services. But even this can improve as tourists get more information, or as the taxi companies offer "roaming" with negotiated rates and reputations.

As for safety, I noted that this could be a reason to licence the cabs, but this in no way requires a monopoly.