Sure it's easy to take a cab. What's more tricky, is not getting scammed. E.g. in Vietnam you'll be looking about various internet sources on which taxi companies are probably not gonna scam you. In France, I had some friends getting scammed in a separate ride from mine.
In general, the ability to know beforehand the price, is golden!
Adding to this: in countries payment can also be a problem, trivially solved via Uber. Take e.g. when I first arrived in South Korea and took an cab from the airport (fixed rates and in cabs in Korea are nice, so not a complaint there), the taxi couldn't take my card, and I didn't have 100k won in cash (accidentally took a luxury cab), so we had to drive around to find a bank that luckily took VISA.
In general, the ability to know beforehand the price, is golden!
Adding to this: in countries payment can also be a problem, trivially solved via Uber. Take e.g. when I first arrived in South Korea and took an cab from the airport (fixed rates and in cabs in Korea are nice, so not a complaint there), the taxi couldn't take my card, and I didn't have 100k won in cash (accidentally took a luxury cab), so we had to drive around to find a bank that luckily took VISA.