
Sir Terry Pratchett
In Terry Pratchett's book Men at Arms, the character Vimes gives one of the best descriptions of the poverty trap you can find. It's known as the boots theory.
Suppose that some good boots cost 50 dollars, but some okay boots cost 10 dollars, and so a rich person can buy the good boots that last them for ten years. But a poor person has to buy the good enough boots, but replace them every year. And so, over ten years, the rich person has only spent 50 dollars on boots, but the poor person has spent 100 dollars.

And so, according to Vimes, poverty isn't just about having less. It's about being charged more for the same things over a period of time.
This works in two ways. The first is to do with capital, because if you haven't got the money in the bank to buy the good boots, then you have to buy the cheaper boots again and again when the money comes in. But the second is to do with the actual price, because poorer households will often have to spend more on the same things as richer households.

If you cannot buy in bulk, if you cannot pay in advance, if you cannot wait for the sale, then you end up paying more. Of course, the boots theory is not just about boots, it's about the loan you have to take, at a rate you have to accept. It's about having to rent a house for three times the price a mortgage would have been on the same property.
Having to buy cheap boots means you have to buy boots constantly. And it doesn't just wear down the boots, it wears down the people wearing them.