I only partially agree with that. There are plenty of more liberal ways to enforce parking payments and rules following. However, cities choose to take advantage of the situation and abuse the system.
For example, SFMTA could easily charge half of what they do for towing and people would still park illegally ONLY when they misunderstood something or lost track of time.
Don't even get me started on meters. Why do chosen people pay $75 for a minute overtime and not all pay for what they overtimed instead? (hint: more money to the city)
At any case, we all know that the system is abused and it has to change at some point. When? That depends on how long all of us are going to let this slide.