They don't make great money so the tip is worth it.

This is the main issue for me. When tips are allowed, the floor for pay/remuneration drops. I would much prefer to know that people are paid sanely for the job they do than to know I am obligated to supplement their pay.

We have direct evidence to the contrary. Uber disallows tipping and pays somewhat substantially less than Lyft.

It's great that you want people to be paid sanely for the job they do, but the fact of the matter is people largely aren't in this industry. Uber doesn't allow tipping, and doesn't pay particularly well. After factoring in depreciation of their vehicle most drivers are going to be bringing in something like $10/hr.

We live in a culture where businesses won't pay their employees sanely. Until that is fixed I want the ability to show my gratitude for a job well done with a tip. "Blah blah use cash!" Sure I can do that, but it's inconvenient for a number of reasons and the reality is that most people won't do it.

Absolutely agree with this point. I hear the same argument for restaurant waiters and I hate this tipping system that even has suggested tipping tiers. It only tells me that owners of these establishments are not paying their employees correctly. I know of places which don't even disburse the tips back to their employees (when tip is part of receipt)!

At least in CA, waiters still get full minimum wage.

Recently some fancy restaurants in NZ have started asking if I want to tip (tipping has never been common practice in NZ). I always refuse and state this exact reason. As soon as customers are expected to tip, workers get exploited.

I'm not tipping you for your own (long-term) good.

NZ has a similar minimum wage to Australia, right?

I think some of it is (stupidly) driven by new credit card / eftpos machines that have the tipping option built in.

Because tipping has a tendency to grow from "bonus for exceptional service" to "obligation".

Why not tip the driver out of your wallet?

Tipping through an app allows the employer to pay them even less because "they receive tips", in the end you're tipping the company that hired them.

This makes drivers expect to be tipped (even if they did usual or mediocre job) and essentially becomes a hidden fee.

Tipping through the app is much more convenient because I rarely carry cash.

And your point is kinda negated by the fact that Lyft usually pays more than Uber.

Lyft currently pays more, because that's probably last thing that keeps them alive. Many drivers work for both, if Lyft would pay same or less then what would keep them there?

As for the negating point, this is not something that happens instantly, but if you want an example then look at restaurants. There's even special minimum wage (currently $2.13) for jobs that receive tips.

Not in California.

US is bigger than California.