Basically what’s been said. Lycopene is the pigment that is staining. It’s hydrophobic and is really good at bonding to plastics for reasons outside my understanding. Soap and abrasion will loosen it, but because it’s hydrophobic it has nowhere to go. The absorbent paper towel gives it something else to bond to.

This might change someone’s life: Instead of washing your spaghetti stained plastic container with a sponge or throwing it in the dishwasher, fill the container to maybe 30% full with hot tap water, add a couple pumps of dish soap, chuck in a paper towel, close the top, and shake. It’s honestly astonishing how effective that is.

DYI

Do Yourself It? Demolish Your Igloo? Despair Yield Index?