Not to mention the experience of calling a cab as a foreigner and having the driver take advantage of you by price gouging you or taking you on unnecessary detours.

You might be overestimating the gap in efficiency. For example, last night, I ordered a pizza for pick-up, and the phone call took exactly 31 seconds. Even apps aren't instantaneous, but if they were, you're only talking about saving less than 1-2 minutes per day. In exchange for those time savings, apps introduce a lot of complexity and overhead: service fees, app updates, device storage, logins, behavioral tracking, etc.

Now, that being said, there are a few unique advantages to apps, like being able to order taxis in a foreign country (as you said), or being able to share your GPS coordinates with the taxi.

For people that don't embody crippling social anxiety, calling is less friction and more effective.

I say this as one of those people, and still struggle to phone people when I know it will bring better results :)