I sense a bit of anger in your last sentence, "why does everyone". For new car purchasers, your solution is possible. For existing owners, that would mean a severe increase in cost of living.
And if you force the government to inefficiently reserve street space for cars, society has to incur the same costs, except non-car owners are forced to unfairly subsidize car owners by bearing those costs.
There is always land available to buy, €10k per square metre for this property for example: https://tranio.com/france/adt/1928891/
Maybe that's too much to park your car, but land has a cost, why should a car owner be allwoed to store their property on public land for free? Can I build a shed in that space instead?