I totally agree with you
750XL. However I would respectfully suggest that there is a big difference between being overcharged £50 by a corporate institution and being quoted £1 more than the
probable cost of a journey driven by a self employed taxi driver in a poverty stricken country.
The point I'm trying to make is that it's easy to let the large denominations distort your perception of the value of money in countries such as Thailand (the quote above being a classic example). When people talk about 'taxi scams' and 'extortion' they are often referring to sums of money which are tiny in the grand scheme of things. 50 Baht is nothing to an expat or a tourist.
In any case, it's much better to negotiate a fare in advance in Bangkok anyway. That way you know the driver is going to get you to your destination as quickly as possible rather than spending ages navigating back streets to 'avoid traffic' (whilst conveniently running up the meter...
). They don't tell you that in the guidebooks...
The allegations about BKK duty free are extreme but there is nothing to suggest that those practices are still going on.