One of the biggest instances of wasted time on any transit route, but especially a local bus route, is what the industry calls "stop cost"- the amount of time it takes to pull to the curb, open the doors, let passengers off, let passengers on, collect the fare, close the doors, and pull away once more. This is why limited-stop buses like Metro's Rapid lines can show such a substantial increase in speed, even without dedicated infrastructure- the stop cost is significantly lower. And while RTA and Omni have done their best to lower stop costs by including double-door low-floor buses throughout their fleets, and encouraging patrons to exit through the rear doors (though this doesn't always work, frustratingly), there is one area of the boarding process that could be significantly improved through a currency modification.
I'm speaking, of course, of the $1 bill. Every other major currency in the western world- the Euro, the Pound Sterling, and the Australian, New Zealand and Canadian dollars- all use coins for amounts below $5, €5, and £5, with each carrying a 1 and 2-unit coin. Transit fares the world over fall into this range- even the most expensive local fare I'm aware of, that of the New York City MTA and Chicago CTA, is $2.25. While magnetic swipe passes and reloadable proximity cards are becoming popular, even in areas with well-developed programs cash fares are common- AC Transit and Muni in San Francisco have accepted the Clipper (formerly Translink) card for years, and yet it is still common to see passengers paying cash on both systems.
And the $1 bill is the most inordinately clunky piece of fare media ever, as any transit passenger is undoubtedly aware. Even crisp bills take time to extract from one's wallet and carefully feed into the farebox reader, and if the bill is anything less than crisp, then you will be trying to pay your fare for quite some time, while an angry mob of passengers gathers behind you.
Compare this to the experience even with paying your fare in dimes- simply drop them in the box and move along. This experience is the only possibility in most of the western world, because the finicky bill acceptor doesn't exist on the bus. I can tell you from personal experience that Translink's fareboxes in Vancouver have slots for coins, passes, and that's it.
Now, the benefits of the $1 coin don't stop at faster public transit- they're more durable, last longer, and save our country the expense of printing all those dollar bills, not to mention that any vending machine transaction is easier and quicker. Oh, and we've already GOT a $1 coin- they're gold, and they've either got a Native American motif or a former President on them. They're dispensed as change from Metrolink and Metro fare machines, and you can get them at most banks.
So why is it that America is still fumbling for singles? I suppose it's the same reason we don't use the metric system, or have universal health care- We're the U.S., and we're special.