Especially not true in many countries where Uber was banned or is in the process of scrutinity. I have never had any dirty in Seoul, or in germany where I live, or in england (as a matter of disclosure I had a few dirty taxi in NY, true, but the vast majority of taxi I took in Dallas or other metropole in teh US were squicky clean). I had a few dirty taxi in Paris, but that was so long ago, and the few taxi I took in the last decade in france were clean too.
Anyway at least for germany I support the regulation and uber being forced to obey it. After all we do not have a medaillon system like in the US, everybody with the proper training driver licence, and the proper governemental check of their money counter, as well as the proper insurance (commercial passenger transport insurance) can become a taxi. In my city we have a lot of different taxi companies, some being simply a single person having repainted their own car (and having the proper papers). Nothing outrageous really, in fact those regulations make a lot of sense.