You are quite right, only one of the varieties I grow is mainstream, Shirley , which is better than the standard supermarket fair, all the others are not available at supermarkets.
Re Yellow Brandiwine, I have grown several yellow varieties simply because they have a better taste than the red ones and the colours give a nice look on a plate, but Yellow Brandywine also is very fleshy, not in a course way but simply denser and more tasty, that one in the photo was big enough to feed a dinner party on its own, one slice constituted a meal, there is a red version that is also very good, but the field in this genus is enormous though many really only replicate others.
Of all the veg grown at home the other best bet is cucumbers, most supermarket cucumbers, in fact all, are tasteless and very watery, whereas certain seed grown varieties are much more fleshy and tasty, I have been growing Diana an F1 hybrid for awhile but others are very similar and are nothing like supermarket cucumbers.
Soft fruit falls into the same category, as all the supermarket varieties are grown for keeping qualities and prolific production, there is no comparison with home grown varieties.
In fact the supermarkets here more than on the continent have killed off many of the fruit and veg we took for granted some years back, the vaiety of Apples for sale in this country is disgraceful, when did you last see James Grieve, Worcester Permain, Beauty of Bath, Reverend Wilkes a magnificent cooker /eater and hundreds of others, I used to deal witha nursery in Kent that supplied over 700 different Apple varieties, you are lucky to see more than half a dozen in the supermarkets and most have been in store so long they taste of cardboard.
I think I will sign off under a different name for these comments, will Percy Thrower do !
but it is a fact whilst our choice of wines continues to expand and encompass the world with more and more grape varieties coming onstream, our fruit and veg contracts evermore.