I'm not being flippant here: customers have routinely shown that for lower prices they'll suffer almost anything, to the point that safer alternatives become uncompetitive.

TfL isn't asking for much here: just that drivers are vetted properly and consistently. Every other firm in London is asked to do it, and complies. If Uber can put them all out of business by saving money on not doing that, the market will make the industry less safe for passengers.

We have voted in people to ensure that doesn't happen, because we want protection from the free market, simple as.