Tomatoes.

Over decades, shop tomatoes have gradually lost flavour to the point where almost all sold in the UK are completely tasteless. So then came vine tomatoes - toms still attached to their twig. They were more expensive - but at least they possessed a hint of flavour. Now - they too are just as tasteless as anything else. SO. Why is it that I can go to any market in Spain and purchase the most unpromising looking fruits - often at little more than a euro a kilo - and they are bursting with  flavour?