I mean, I can understand wanting to start in dense places. But those are also the places where public transit is a viable existing solution.
Personal transit just looks incredible inefficient and unscalable if everyone would use it. I could totally see it as a last resort solution for situations where nothing else is available, but that's an unattractive market that isn't going to make anyone rich.
Ambulances are for emergencies. An ambulance could be dispatched depending on availability, but the dispatch team has more experience with this than I do and so they - like the hospital's initial triage team - would put me in the "injured but not dying" category and maybe I get an ambulance in an hour or two depending on other priorities.
They don't want me to go home and fall asleep, because it is possible that I have a brain injury and will never wake up, but their advice is going to be "Can you get somebody else to drive, or maybe call a taxi?" not "We will Blue Light an ambulance to you ASAP".
In an urban area the "last resort" cases add up. The last time I was in a taxi it was the middle of the night, and I'd just smashed my head open, so I had concluded that I must not trust my own judgement and should seek immediate medical attention, buses don't run in the middle of the night (on that route)