First we have to understand that, all things being equal, cars "win" by default on the roads. They are bigger, heavier, faster and more powerful (thanks to burning fossil fuels), and the operators are more reckless and inconsiderate due to being shielded from the outside world. That means their presence on the roads automatically makes it more dangerous and unpleasant for everyone else.
Second notice that primary routes are always designed for cars first. Every two places has a primary route connecting it. Depending on the importance of the route that route will have some level of protection against things like flooding, subsidence etc. and also be generally higher quality. That primary route is always for cars. Due to the above, that generally makes it undesirable or often practically unavailable for non-motorised traffic. See, for example, dual carriageways. Technically everyone has a right to use them by any means (they have paid for it, after all), but you'd be crazy to walk/cycle down one.
Third notice that cars are basically untouchable. It's considered a perfectly acceptable and normal part of driving to put people's lives in danger by driving too close and too fast etc. But nobody dares touch a car. They have the capability of killing or seriously injuring people, but people don't have the capability of killing them (the cars). The police will laugh at you if you report a car driving too closely. But scratching a car or something? Police will be on your case. Basically, we value metal boxes on wheels more than people's bodies.
Fourth notice that every part of the road network is designed to make it easier for cars at the detriment of pedestrians and cyclists. Why does a pedestrian need to press a button to cross the road? Why, upon pressing the button, must the pedestrian wait to cross? Why doesn't the light cycle start immediately? There is absolutely no sense at all in making the pedestrian wait. But everyone is used to it and doesn't question it; it's just the way it is. But what it does is makes being a pedestrian a third class status. It's these little things, like having to sit at the back of the bus, that chip away at people's ability to feel like an equal member of society. If you walk or cycle you are under no illusion that you come second to cars. It's little wonder people choose the car if they can.