Your comment raises an important concern - safety and the distribution of spheres of interest. I must admit I hadn't considered these factors when writing the article. In my mind, I pictured a calm European city like Barcelona. I would be thrilled if the first city to implement this taxi-bus system was Barcelona, and I see Los Angeles, with its upcoming Olympics, as the second most promising.
Of course, the taxi-bus system will not solve the safety problem on its own, but I believe it won't be any less safe than any other form of public transport. Therefore, all other things being equal (as we mathematicians say), the taxi-bus system should be better.
there is probably a close correlation between price / safety. Minibuses seem often to be the least expensive option, so perhaps mostly used by those who have least money. I'm going to guess they don't attract vagrants in the same way a train or bus might do - perhaps something to do with the small size of the vehicle / inevitable proximity with other passengers and / or motivated gate keeping by the driver-manager
Of course, the taxi-bus system will not solve the safety problem on its own, but I believe it won't be any less safe than any other form of public transport. Therefore, all other things being equal (as we mathematicians say), the taxi-bus system should be better.