How is industry regulation different in those markets? When you get ripped off, what is your recourse in Amman, Athens, or Madrid? What can you do about it in Berlin or Manchester?

That's the key...taxis are heavily regulated in the US, and the penalties are strict for overcharging customers, not using the meter, etc. The cost of taxi medallions in major cities is extremely high, so taxi operators take extreme caution not to get in trouble.

In countries I've been to where regulation is more lax, or where bribes are common to circumvent regulation (e.g. Philippines, Malaysia, Thailand), drivers were more likely to try to rip you off, like trying to charge you a flat rate that is double or triple what the meter would have been. In places I've been where regulation is more strict (US, Singapore, Hong Kong, Japan), taxi drivers have been more honest (e.g. insisting on using the meter, not trying to charge extra fees).

It tends to be the wealthier countries I've been to that are stricter with regulations.

Regulations in Spain and Greece are somehow strict: a special licence, somehow equivalent to the New York medallion is required.

Furthermore, at least in Spain, being "a taxi driver" is a form of cultural identity. Typically, regulations specify that either the licence holder ora first-degree relative should drive the car.

I had good experiences with taxis in Spain (Barcelona), so it appears the regulation works. We asked our hotel what the rates should be to go to certain places, and the meter worked out to be in line with those. Maybe it's different in Madrid...

In Barcelona I had a ride where the taxi driver spent the whole time moaning about how short it was... (he claimed to have misunderstood the destination when he received the request, implying that he would have refused).

No rip-off, though, just very poor customer service that time. Again, not all were like that, but it's harder to come across a driver like that in Germany or Britain. Perhaps it's just some superficial pattern of behaviour.