Not sure if different to here, but all cars cannot be older than 8 years old and I haven't been in a clapped out car yet.
They warn you if they surge charge before you book the job, had it only happen once and there was a 2.1 times increase on price so just waited 30mins till it finished. Not ideal for everyone I understand but you don't get surprised by it, if its too much get a taxi! And they don't take you a long way round, they follow a GPS through Uber and you can too through the app.
This is all based on Uber in Aus though, may be different in UK.
I just can't see how being charged $21 to get to the airport through Uber or $48 through a Taxi is a bad thing for the consumer.