decentralization, like what you describe in cab services, dilutes power. that's it. that's the only reason necessary to explain why it'll never be allowed to stay decentralized (and decentralizing). in many countries/cities, cab liceneses are quite a corrupt business; it comes down to who you know that can hook you up with one (kinda like drugs but without the raw illegality). typically the driver does not own neither the cab nor the licence; they're just some poor employee without many options.
>It would be fully decentralized, except for the payment part. If you have everyone on your platform you don’t need to issue tokens and other bullshit. Just build something useful and they will come.
sounds naive, you know who will also come if you start to get popular with your platform? the government/police who really act quite like a mob. them people who want/need/like to be powerful. because any such platform which is popular has power, power ripe for 'centralizing'; just say it's for safey and legality instead of 'centralizing'.