There are already two powerful forces protecting consumers, reputation and tort law. A taxi service with poor service will not be in business for long, because its reputation will crumble, and if the service is truly negligent (for example, by driving vehicles that are in dangerously poor shape), the customer who is harmed can sue, not to mention traffic laws that already punish any driver who endangers other drivers on the road.
You say that foreigners don't know anything, but I think most travelers would disagree. When I travel to a foreign country, I am still fully capable of researching the best hotels and restaurants, despite not speaking the native tongue. Taxi service isn't any different.
I'm not saying all consumer protection laws are unnecessary, but you have to remember that regulation has a cost. Of course, there's the cost in tax money, but also the fact that regulations are slow to change when necessary. Perhaps the largest risk is regulatory capture, which we've clearly seen in the taxi industry in a number of places. For example, from the linked article:
> In France, the proposed remedy was simple: a mandated delay of 15 minutes between ordering a ride from Uber and the passenger pick-up.
I find it inconceivable that this sort of regulation is meant to protect consumers. Clearly its only purpose is to protect the profits of traditional taxis.