I mean that surely, the existence and political power of taxi unions are orthogonal to the decision by various government to protect the taxis!

The governments have just acted in the interest of the public, as usual.

Dunno, not much happened. Uber came in, broke the law, and went. The law already existed, and the taxi organizations aren't particularly powerful. Note that anybody can start driving taxis here after some mandatory course and exam, there's no bullion system.

Maybe, but I would still be surprised if whoever gives this courses and exams did not lobby for them to be applied to uber

as you said, "it broke the law": the law is made to benefit incumbants, not newcomers.

It is true that taxi organizations lobbied ahainst Uber, but they had public opinion on their side. Uber is the one that was perceived as exploitative.