This is ridiculously complex, and thinking you can encode every possible eventuality in law or code is frankly not a serious suggestion. You need the "slack" exactly because it's just not feasible to do so. (Also: so many things can go wrong with your "facial detection" suggestion: internet not working, error in facial detection, broken equipment – never mind the privacy implications, or the cost of building and maintaining all of this, which would certainly be far far higher than any corruption, and still won't actually prevent corruption because drivers could still just let their mates pass without paying).

And yes, giving people autonomy also means they can do bad things. And that's something we can live with, and it's far better than forbidding them from doing good things. Your distrust of people borders on the misanthropic.