That is the equivalent of "I could build that in a weekend" that you often hear from inexperienced devs that have no idea what they're talking about.
In fact, we had the perfect experiment in Austin, TX, where a couple years ago the city essentially voted to kick out Uber and Lyft (required fingerprinting of drivers) before the state legislature passed a law overruling the city. There were lots of competitors that flooded in to fill the vacuum. They ranged from "barely if even functional" to "OK". I was even a big fan of Ride Austin because it was a nonprofit, but I'm not going to pretend its apps were anywhere close to Uber and Lyft's.