Why don't you go and check any of the Uber drivers forums? You will be surprised. Uber drivers give you at most 4 if you don't tip. You can easily check your Uber rating (as a passenger) on the Uber website. I've been tipping Uber drivers since I learnt about this repugnant attitude. Very rarely the tips are declined, it's more often that Uber drivers hint about getting them. Anyway, my Uber passenger rating is 4.9. And compared to me, Uber drivers think that you're a cheapskate.