Q.what causes lack of fruit/vegetable growth, but intense foliage?
Small tomatoes, beets, radishes, peppers etc., lots of leaves and good vines, stalks

Is it possible that you are over-fertilizing with a fast release high Nitrogen chemical fertilizer or manure? If so, water copiously to flush and leach the excess chemistry, then wait a month or two and switch to a more balanced slow release natural source organic fertilizer. Or at least a more balanced NPK fertitlizer. The P is Phosphorus and the K is Potassium, which have more to do with flowering, fruiting and rooting. High N stimulates vegetative growth at the expense of flowering and fruiting.