I can't speak to London in particular, but what you say also holds for the US. And I wonder if they took the same approach because of a similar set of circumstances.

In the US, Uber's aggression was pretty clearly the only way to ever launch - they had to (1) break the rules, (1) delay in court, and (3) grow like crazy, so that by the time their law-breaking is proven, they're too popular to outlaw.

Now, their incentives are different because they're the incumbent. They WANT to work under heavy regulation (just like the taxis did!). So, if the same is true in the UK, I wonder if it still makes sense to layer it on, knowing that eventually the other players will have to overcome the same barriers.