That works in cities like Zurich where there are lots of buses going absolutely everywhere and are almost always perfectly on time. I worked there for 3 months and my 8:23am city bus was there on the dot pretty much every day. It would often get to the stop at 8:21 and wait till 8:23, like clockwork. There was no payment system on the actual bus, people had to take care of payments outside the bus so as not to delay boarding.

In the US, buses largely don't need to get you where you need to go, are never on time, delayed at every stop by a line of people fumbling for how to shove crumpled dollar bills into the machine. The governments have no plans to fix any of this, so I welcome the private sector to step in and provide a bus solution in the meantime that is fast, clean, and efficient.

Slack is good, too much slack is wasteful.

Charge them their full amortized share of the road, raise rates if congestion becomes a problem.