You are wrong that prices falling prior to deregulation proves that deregulation wasn't a factor in declining prices. A graph of numbers showing decreasing cost

You are wrong that prices falling prior to deregulation proves that deregulation wasn't a factor in declining prices. A graph of numbers showing decreasing costs measures purely quantitative factors. The trend continuing completely excludes qualitative factors, of which you must understand to properly understand what is going on. For example, the article says that what was expected to happen was that costs would fall because there would be an influx of hundreds of competitors. That in itself is a misunderstanding of qualitative factors. Imagine there being 100 different airlines. More than half of them would be incompetent. The correct qualitative understanding of the situation is that deregulation allows the most competent airlines to consolidate/buy underperforming ones. Did service really get worse? Or is the difference really just that these airlines are now able to transport way more people at a cheaper cost because they are no longer catering to smokers who like to leer at PANAM blondes in short skirts? Also, regulation around marijuana has not decreased prices. This is obvious because in places where marijuana is now decriminalized people still prefer to buy from illegal sellers... because it is cheaper.