Uber is great. But....
Imagine someone coming into the pub with a trolley selling bottles for a quid, half the price of the pub.
That's great for the punter "We're being ripped off by the pub" you'd say. But the chap with the trolley isn't paying living wage, or lighting, or health and safety costs, or for fire extinguishers, or smoke alarms etc etc.
So yes, uber is great but this is London flexing its muscles and saying "Sort your shit out and get back to us, then we'll renew your licence."