75k is a pittance compared to the damage you could do to another person's property or life while driving. That's the whole point of the legally mandated liability insurance--for most people getting in an accident that results in injury to the other party would be financially devastating. And even worse would be having someone hit you and put you through 250k of medical care with no ability to pay.

Thousands of people are injured every day in car accidents in the US and about 100 are killed, so its not some kind of unicorn situation.

If you want to argue about driving being a necessity to live and work, that's a completely separate discussion from why liability insurance is necessary.

Well that's the thing. It's about ensuring that there's a legally predefined amount of money available to pay for damages you cause while driving. It's not going to be cheap. The dmv holding it as cash is merely the alternative to insurance pooling everyone together, charging them according to risk and the cost of doing business, then paying it out whenever necessary.

The only real alternative would be forcing you to actively maintain that amount in free credit, which would probably be difficult and have a fee associated with the risk of inability to pay, especially as you're not guaranteed to survive a crash you're at fault in.

That’s why people get liability insurance instead,

The average new car is 50k, many cars are a lot more and medical expenses can be crazy. If you accidentally total a 100k sedan and the driver ends up with a broken bone you could be forced essentially into a life of indentured servitude with 50% of your wages garnished for life