What for? This is right up there with the short sighted ppl asking for animation for cyberware. It's a gimmick that ppl will get bored of after 5 minutes so the devs likely realized that.
1. There's fast travel in the game, most players don't spend time driving from point A to B. I do most of the time, but I don't assume my experience represents the vast majority.
2. You'd have no control meaning you'll get stuck in traffic somewhere, get bored when it takes too long and decide to drive yourself or just fast travel.
3. Think about these suggestions from the point of player experience before making these posts based on something you saw someone say somewhere. Does it really add anything of value to the player experience? Is it worth investing time and resources? This is not.
The pretentiousness of your response matches its foolishness.
1. I, as I'm sure most players, sometimes fast travel and sometimes drive. Having a taxi as an option would not be a rarely used feature. I'm sure many would enjoy this alternative at times, even if you personally would not.
2. As for getting stuck in traffic or bored, it would be all too easy to "Hold F to skip to destination" option if one gets bored of the ride. This feature already exists in the game so your #2 is a non-issue.
3. Regarding player experience, try taking your own medicine on this one. This feature would definitely add value for player experience when I've just wrapped up a quest and need to travel somewhere, but I want to get up in real life and grab a drink/stretch, check my phone, tidy my room, whatever. The game also delivers information frequently via radio and has a kickass soundtrack. It would often be desirable to just sit and let the game drive you to your destination while you soak up information/ambience. Just because you personally don't like an idea doesn't mean it objectively detracts from player experience as you claim. This feature would undeniably enhance the game.
The biggest factor however, as you point out, is the time an effort that would need to be invested. Obviously the benefit of this feature is relatively slight and if it would take a ton of coding then I agree it wouldn't be worth it. However, it is obvious from the mechanics already in the game that they could practically enable such a taxi feature with the push of a button. Since the overall time investment would be minimal, this would be a great feature to add as OP suggests.