What could governments do to reduce cars on the road?

Not having to wait 55 minutes if you ever miss a train, or hoping a theoretical 15 minutes for a bus with a very high chance of skipping runs or breaking down. And a system to actually be where you want to be, instead of then having to walk multiple kilometers after reaching the central station.

Stop making driving hard, start making walking and mass transit easier. They are not the same thing!
Making driving hard just means people either spend more time doing it or they avoid the area as not being worth the trouble.

Investing in public transportation and bicycle infrastructure has always been a good way of getting cars off the road.

A lot more public transportation ( tram, bus, brt, subway, depending on the budget), mixed zoning, pedestrian zones/streets, proper bike lanes, expensive parking inside the city, bike lease (like Vélib'in Paris), trains to facilitate transit between zones without good public transportation access (like suburbs or countryside) and city center.
- Sorry, more public transport works only to an extent, many examples over the world. Germany, for example, makes it kinda hard and hurtfully expensive to even get a driver's license. Above 2000 Euro and at least a year in the cities. Many just give up. But that's not the way either. I for myself would simply forbid large SUV and other large vehicles in any denser populated areas, massively support the hydrogen and fuel cell technology, stop listening to the greedy mofos who tell everyone electric cars are the future, they are not in the current state of development, only for short distance deliveries. Movement of any goods on rails, small (electric, hydrogen) vehicles to the shops. More space for bicycles is a way, but it works only to an extent, too.

Edmonton Alberta wants to introduce a concept of a 15 minute city, where wherever you are in the city it will be a quick 15 minute walk to most of your daily needs
- That's incredible. I would love to live in this sort of a city!
- Don't let the conservatives hear you say that. They apparently think that "15-minute city" means "you can't travel more than 15 minutes from your house" or "you can only drive your car for 15 minutes a day" or some other such nonsense.

Accessible & free public transportation options
Mixed zoning, so places where people work/eat/shop/etc. can be near where they live

The answer is well planned mass transit. I have been to Tokyo. Took their bus, subway, and bullet train. They work flawlessly together connecting millions of people. I believe the public transit in Japan runs far more efficient than the ones in the US. They also are profitable unlike the one here swimming in debt.

Building networks of reliable, consistent, affordable and SAFE public transportation

Walkable cities and mass transit. I've traveled in Tokyo, Seoul, Taiwan, Hong Kong, and Singapore. All of them have very good public transport.

Porverty.
Before Vietnamese Sai Gon was still called Sai Gon, there was a lot of car on road.
When Sai Gon change name to HCMC (i.e: communism triumph over greedy capitalism), lot of cars disappeared, replace by bycycle, then motorcycle until today.
So, porverty to the point that convert car from necessity to luxury is a best way to reduce car.

Encourage remote work wherever possible.
- Bosses hate this one. The things they'll do for a full office...

Improve rural connectivity to allow more people to work remotely from a non-urban/suburban area. Starlink is decent, but still not great for video calls.