Perhaps if you have a big family it's hard, but if there's only 2-3 of you, there's no reason to eat unhealthy.

Take the Lentil Dish I mentioned above.

Bag of Lentils: ~$1
Bag of Split Peas: ~$1
Vegetable Stock: ~$3 (but totally optional, just a personal splurge)
Kale: <$1 (only used some)
Mustard Greens: <$1
Butternut Squash: $3

Max Total cost of meal: ~%10

I made it over a month ago and I'm STILL eating it. Even for a family of 5 (like I grew up in), we'd have had substantial left overs. And it's a very healthy dish that I can make multiple variations of without spending any more money than that. Furthermore, the Kale and Mustard greens I used were delicious tossed in some oil and lemon juice, or lightly sauteed.

You just have to shop around and stop and LOOK. Some more well priced vegetables:

Cucumbers (I buy these for around 79 cents)
Spinach (Sometimes)
"Old fashioned" Greens (mustard greens, Collard greens, etc...)
unpeeled carrots
Parsley (I've seriously made myself a cucumber-parsley green salad with some canned black olives. Laugh if you want, but it was DELICIOUS.)

Anyway, my point is that you do have to look more, and you might not be able to buy what you "want", but it is perfectly possible to make full and healthy meals with plenty of fresh fruits and vegetables. Particularly if you're only shopping for yourself or one or two others.