It's reasonable in some cases, but not with Uber. I think that they are trying to win the margin game, Amazon-style - if nobody can undercut them on base price, then new players cannot challenge them. So, for frequent customers a "discount" may be appropriate, but it makes acquiring new customers much harder ("UberX: Cheaper than a taxi when there's a discount").

The other

They'd fall afoul of some laws in the UK (probably EU too). In the UK, you can't have permanent "discount" prices without a certain period of time in between each so-called sale. This was mainly targeted at furniture sales companies who seemed to always be advertising a 50% off sale of some sort. But I imagine it could catch something like Uber if they never actually offered their real price for a significant amount of time (I think it was 3 months or so?)

I'm not sure that upping the base price and then discounting it is a winner for Uber. They advertise on their base price -- they want it as low as possible.

The existence of taxis as a very ready basis for comparison makes it different than airlines. Uber can (and, you know, does), say "We're 30% cheaper than taxis!" Then, sure, surprise, sometimes you see that actually they're 3x more expensive than that. But at that point you've got the app open and are seconds from doing the hailing -- that's gotta have a certain level of stickyness.

If Uber said instead, "We're twice as expensive as taxis!" significantly fewer people would even open the app to find out that actually, right now, they're way less expensive.

Man, I wish I could fly to SFO for $345. I'm looking to go there soon, and the schedule I get is:

Round trip, SFO-PVG: $700

One way, PVG-SFO: $1300

I'd really like to get in on that PVG-SFO flight for under $700...