Barrier to entry typically means something something physical or formal. Needing to build a billion dollar fab is a barrier to entry in the micro chip business, needing more than a decade of training is a barrier to entry to being a doctor. Having to produce a better product than your competitor isn't generally considering a barrier to entry, that's more on the competitive advantage side of things. Coca-Cola has an amazing brand, and that's very difficult to complete with. Uber works really, really well, there are a lot of details that aren't just "push button, get car". I've used used a few of the alternative apps, and while they generally clear the bar of "working", they are a long way from being as good as Uber. That said, it's a one way ratchet, and some of the apps are catching up quickly.

Sidenote on barriers to entry: one of the original meanings of "disruption" was the tearing down of barriers to allow new entry and competition in a field. Ubers steamrolling of medallion schemes constitutes such a kind of "disruption". Of course, once disrupted, there's no closing the door behind you.