The taxis where I live are none of the things you listed, they are clean, and the drivers are (mostly) polite. They also know where they are going.
This has not always been the case, the industry was heavily regulated and protected until the mid 1980's, which made taxis expensive and inflexible (a taxi could not be hailed from the street for instance, passengers could only be picked up from taxi stands).
Then came deregulation, almost completely, and several times a smoking wreck would break down halfway to my destination, (if the driver even knew where he was going) which usually involved shouting and threats.
I don't use taxis as much as I used to, but it sounds like the issue where you live is poor regulations.