Sure, as long as the price gets negotiated in advance. The problem is the sudden change in terms. This is the free market in the same way that a NY real estate

Sure, as long as the price gets negotiated in advance. The problem is the sudden change in terms. This is the free market in the same way that a NY real estate developer telling a sub "I'll pay you 40% of what we agreed, if you don't like it contact my legal department" is the free market. The taxi driver has your luggage; they've eroded the time you thought you had and made you desperate; they now change the terms.