I guess you haven't taken many taxis in foreign/non-first-world countries? You can haggle all you want, but if the man is holding your luggage hostage, you'll have to pay or get the authorities involved...which may be difficult if you don't speak the local language. And the fact that all the driver has to say is "We never agreed to that price beforehand"

> I guess you haven't taken many taxis in foreign/non-first-world countries?

That would be a wrong guess.

And you'd have a hard time holding my luggage hostage, I have a single small bag that goes with me in the passenger compartment. Large suitcases are a vulnerability.