How is the contrast between the past and present condition of the people described?

The contrast between then and now is drawn with reference to their eating habits and clothing.

First, it is stated that those who were previously used to the finest delicacies now search the streets for a scrap of food while they are perishing. Proverbs 23:3, Proverbs 23:6 refers to delicacies as the food of royals and rich people. Previously these people fed on the choicest of items (see also Genesis 49:20). But in the catastrophe which has overtaken them, they now wander the streets, looking for anything to eat.¹ The expression in the streets is a recurring theme in Lamentations 4 (see Lamentations 4:1, Lamentations 4:8,Lamentations 4:14, Lamentations 4:18). The contrast between the past and present is thus stated as a time of abundance of delicacies in the past from where they have moved to minimal or no food scraps at all. It is a contrast of riches to poverty.²

Second, those who were used to the finest attire now scavenge for any scraps on an ash heap and possibly live there as well. Purple refers to their expensive clothing. It was obtained by the dye of scale insects. To extract it was a costly process, which made the fabric dyed with it extremely expensive. Only the rich could afford it (see Proverbs 31:21). This expensive fabric may also refer to blankets produced in this way to wrap young children.³

The contrast in their living conditions was worked by God. Like Job, the people moved from great wealth and abundance to sit on an ash heap (see Job 2:8). God drives people from places of prominence to places of utter despair. However, he may also reverse this contrast in conditions when he raises the needy from despair to abundance (see 1 Samuel 2:8; Psalm 113:7).⁴