The OECD includes countries like Mexico, Turkey, and Colombia that are definitely less developed than the rest of the list. Hell, looking at the IMF figures, half the European countries on that list count as "developing" too, especially the less-taxing ones. Don't think I agree with them, but I'm not an economist so hey.
The UK is a bit above average tax burden as share of GDP for the OECD. It is not particularly “low tax by developed world standards”.